THE  SILVER  SUNBEAM: 


%  ^radical  anir  ^mtixml  fotxt-^Qok 

ON 

Sun  Drawing  and  Photographic  Printing: 

COMPREHENDING  ALL  THE 

WET  AND  DRY  PROCESSES 

AT  PRESENT  KNOWN,  WITH 

Collodion,  Albumen,  Gelatine,  Wax,  Resin,  and  Silver ; 

AS  ALSO 

Heliographic  Engraving,  Photolithography,  Photozincography,  Ce- 
lestial Photography,  Photography  in  Natural  Colors,  Tinting 
and  Coloring  of  Photographs,  Printing  in  Various  Col- 
ors ;  the  Carbon  Process,  the  Card-Picture, 
the  "Vignette,  and  Stereography. 


EY 

J.  TOVLER,  M.D., 

PRENDERGAST  PROFESSOR  OF  NATURAL  PHILOSOPHY;  COLLEGE  PROFESSOR  OF  MATHEMATICS, 
AND  ACTING  PROFESSOR  OF  MODERN  LANGUAGES,  IN  HOBART  COLLEGE  ;  PROFESSOR  OF 
CHEMISTRY  AND  PHARMACY,  AND  DEAN  OF  THE  FACULTY  IN  GENEVA  MEDICAL  COLLEGE; 
AND  EDITOR  OF  "  HUMPHREY'S  JOURNAL  OF  PHOTOGRAPHY." 


And  God  said,  Let  there  be  light:  and  there  was  light." 
 4  


NEW-YORK: 
JOSEPH  H.  LADD,  PUBLISHER,  No.  60  WHITE  STREET. 
1864.  , 


Entered,  according  to  Act  of  Congress,  in  the  year  1863,  by 

JOSEPH    H,  LADD, 

in  the  Clerk's  Office  of  the  District  Court  of  the  United  States  fo*  the 
Southern  District  of  New-York. 


CONTENTS. 


CHAPTER  t 

PAGES 

History  of  Photography,   9 

CHAPTER  II. 

Preliminary  Observations,   21 

List  of  Photographic  Outfit,   25 

CHAPTER  III. 

Specialties  in  reference  to  the  Articles  in  the  preceding  Chapter — the  Glass- 
house, etc.,   27 

CHAPTER  IV. 

Specialties  continued — The  Camera  and  the  Lens,   84 

To  find  the  Principal  Focus  of  a  Lens,   86 

To  find  the  Equi-distant  Conjugate  Foci  of  a  Lens,   86 

To  find  the  Comparative  value  of  two  Lenses  or  Combinations  which  produce  the 

same  sized  image  of  an  object  at  the  same  distance,   87 

To  find  the  magnifying  power  of  a  Lens  or  Combination,     87 

To  find  the  comparative  magnifying  power  of  Lenses  or  Combinations,   87 

To  find  a  Single  Lens  equivalent  in  power  to  a  Compound  Lens,   87 

To  ascertain  whether  a  Combination  is  corrected  for  Spherical  Observation,   87 

To  ascertain  whether  a  Lens  or  Combination  is  corrected  for  Chromatic  Observation,  88 

How  to  buy  a  good  Lens,     39 

CHAPTER  V. 

Specialties  continued — The  Camera,   42 

CHAPTER  VI. 

Specialties  Continued,   46 

Dark-Room,   4ff 

Work-Room,   49 

CHAPTER  VII. 

Collodion,   51 

Preparation  of  Pyroxyline,   52 

Formula,  No.  1,  for  the  preparation  of  Pyroxyline,     53 

Formula,  No.  2,  for  the  preparation  of  Pyroxyline,   55 

Formula,  No.  3,  for  the  preparation  of  Pyroxyline,   55 

Formula,  No.  4,  for  the  preparation  of  Pyroxyline,   55 

CHAPTER  VIII. 

Ether  and  Alcohol,   56 

Ethyle  Group,   56 

Ether,     5S 

Alcohol,   59 

Decomposition  of  Collodion,   61 

Preparation  of  Glycyrrhizine,  -.    63 

Preparation  of  Nitro-glucose,   63 

CHAPTER  IX. 

Collodion  Sensitizers — Iodides  and  Bromides,   65 

CHAPTER  X. 

Preparation  of  the  Iodides,   69 

Iodine,     69 

Properties  of  Iodide,   70 

Preparation  of  Hydriodic  Acid,   70 

Iodide  of  Barium,   71 

Iodide  of  Calcium,   72 

Iodide  of  Lithium,   72 

Iodide  of  Potassium   72 

Iodide  of  Sodium  and  Iodide  of  Ammonium,   73 

Iodide  of  Cadmium,   73 

Impurities  of  the  Iodides,     73 

jfesto  of  the  purity  of  the  Iodides,  ... . .   7-1 


iv  CONTENTS. 

CHAPTER  XX  page 

pROMINR,   75 

Preparation  of  Bromine,   75 

Hydrobroniic  Acid,   76 

Bromides,   76 

Preparation  of  the  Chlorides,   76 

Preparation  of  Chlorine,   77 

Properties  of  Chlorine,   77 

Chloride  of  Lime — Chlorinetted  Lime,  etc.,   78 

CHAPTER  XII. 

Normal  or  Platn  Collodion,  Iodized  Collodion,  Bromo-iodized  Collodion,   79 

Bromo-iodizing  Solutions,   80 

Formula  of  Lieut.-Col.  Stuart  Wortley,   80 

Ommeganck's  Formula  for  Portraits  and  Landscapes,   81 

Formulas  of  Disderi,   81 

Formula  for  copying  Collodion,   83 

CHAPTER  XIII. 

Silver— Salts  of  Silver,   84 

Properties  of  the  Nitrate  of  Silver,   88 

Photographic  properties  of  the  Nitrate  of  Silver,   88 

Preparation  of  the  other  Salts  of  Silver,   90 

Hyposulphite  of  Silver,  ,    90 

Iodides  of  Silver,  '    90 

Iodide  of  Silver  for  the  Silver  Bath,   90 

Bromide  of  Silver,   91 

Chloride  of  Silver,   92 

Photographic  properties  of  the  Chloride  of  Silver,   93 

Other  uses  of  the  Chloride  of  Silver,   93 

CHAPTER  XIV. 

Reducing  Agents — Developers,   94 

Iron  Developers,   97 

Nitrate  of  the  Protoxide  of  Iron,   97 

Sulphate  of  the  Protoxide  of  Iron,   97 

Double  Sulphate  of  Iron  and  Ammonia,   98 

Sulphide  of  Iron,   98 

Tannic  Acid — Gallic  Acid — Pyrogallic  Acid,   98 

Preparation  of  Tannic  Acid,   99 

Preparation  of  Gallic  Acid,   100 

Preparation  of  Pyrogallic  Acid,   101 

Acids  in  Developing  Solutions,     102 

Acetic  Acid,   103 

Formic  Acid,   104 

Photographic  uses  of  Formic  Acid,   105 

Citric  Acid,   105 

Citrate  of  Soda,  106 

Photographic  uses  of  Citric  Acid,   106 

Tartaric  Acid,   107 

Preparation  of  Tartaric  Acid,   107 

CHAPTER  XV. 

The  Nitrate  of  Silver  Bath,   109 

Preparation  of  the  Sensitizing  Solution,   110 

Formula,  No.  1,   110 

Formula,  No.  2,   Ill 

Formula,  No.  3,   Ill 

CHAPTER  XVI. 

The  Developing  Solutions,  <   114 

Sulphate  of  Iron  Developer,  Formula  No.  1,  for  Ambrotypes  and  Melainotypes,  -   114 

Formula,  No.  2,  for  Negatives,   115 

Formula,  No.  3,  for  Negatives,   115 

Formula,  No.  4,  for  Negatives,   115 

Disderi's  Developer,   115 

Lieut.-Col.  Stuart  Wortley' s  Developer,   116 

Meynier's  Developer,   116 

Hockins's  Developer,   116 

Waldack's  Formulas,   116 

CHAPTER  XVII. 

Fixing  Solutions,  ..  .  118 

Cyanogen,   113 


CONTENTS.  V 


PAGE 

Preparation  of  Cyanogen,   118 

Hydrocyanic  Acid— Prussic  Acid,  ,  :   119 

Cyanide  of  Potassium,.   119 

Sulphocyanide  of  Potassium,   120 

Sulphocyanide  of  Ammonium  „   120 

Hydrosulphocyanic  Acid,  .                                                          . .  120 

Hyposulphite  of  Soda,..   120 

Formulas  for  fixing  Solutions,   121 

Formula,  No.  1,  with  Cyanide  of  Potassium,   121 

Formula,  No.  2,  with  Hyposulphite  of  Soda,. .    121 

Formula,  No.  3,  with  Sulphocyanide  of  Ammonium,   121 

CHAPTER  XVIII. 

Intensifiers,   122 

Preparation  of  Bichloride  of  Mercury — Corrosive  Sublimate,  125 

Preparation  of  Sulphide  of  Potassium — Hepar  Sulphuret,   125 

Preparation  of  Sulphide  of  Ammonium,  125 

CHAPTER  XIX. 

Wet  Collodion  Process,  ,  1 27 

Collodion  Positives — The  Melainotype — the  Ambrotype,   127 

Ambrotype,   128 

First  Subdivision — Preparing  the  Class,     128 

Second  Subdivision — Coating  the  Class  with  Collodion,   129 

Third  Subdivision — Sensitizing  the  Collodion  Film,   180 

Fourth  Subdivision — Exposing  the  Plate  in  the  Camera,    131 

Fifth  Subdivision — Developing  the  Picture,   131 

Formula  for  Developers,   132 

Sixth  Subdivision — Fixing  the  Image,   133 

Remedy  for  Fogginess,   133 

Seventh  Operation — Drying  the  Plate,   135 

Formula  for  subdued  Contrasts,   136 

Eighth  Operation — Coloring  the  Picture,   136 

Ninth  Operation — Varnishing  the  Image,   136 

Varnishes,   137 

Tenth  Operation — Background  for  Collodion  Positives,   188 

Black  Varnishes,   138 

CHAPTER  XX. 

Alabastrine  Positives,   140 

Alabastrine  Solution,   110 

CHAPTER  XXI. 

Melainotype— Ferrotype,   142 

Operation,   142 

CHAPTER  XXII. 

Collodion  Negatives,   144 

Negative  Developers,   145 

Formula,  No.  1,  Iron  Developer,   145 

Formula,  No.  2,  Pyrogallic  Acid  Developer,   146 

Fixing  Solutions  for  Negatives,   147 

Formula,  No.  1 — Hyposulphite  of  Soda,   147 

Formula,  No.  2 — Cyanide  of  Potassium,   147 

Intensifying  or  Re-developing  Process,   147 

Formula,  No.  1 — Depositing  Fluid,   147 

Formula,  No.  2— Stock  Bottle  of  do.,   147 

Depositing  Operation,   147 

Intensifying  Operation,   147 

Formula,  No.  1 — Nitrate  of  Silver,   147 

Formula,  No.  2 — Pyrogallic  Acid,  (Stock,)   148 

Formula,  No.  3—      "         "      148 

Varnish — Formula  for  do.,   149 

CHAPTER  XXIII. 

Transfer  Process  of  Collodion  Positives  on  Japanned  Leather,  Linen,  Paper,  etc.  150 

Black  Japan,   150 

Transfer  Paper,   151 

CHAPTER  XXIV. 

Collodion  Positives  on  Glass  by  transmitted  Light—Transparent  Positives,.  . . .  153 
CHAPTER  XXV. 

Enlargement  of  Negatives  by  the  Ordinary  Camera,   157 

Reflectors  used  as  Condensers  of  Light,  158 


vi 


CONTEXTS. 


CHAPTER  XXVI.  pages 

Transparent  Positives  by  Contact  by  the  Wet  Process,   159 

CHAPTER  XXVII. 

Collodion  Negatives  or  Positives  copied  from  Collodion  or  Paper  Positives,...  160 
CHAPTER  XXVIII. 

Stf.reographic  Negatives  and  Landscape  Photography,   164 

Instantaneous  Stereographs,   1G6 

Instantaneous  Process  of  Lieut. -Col.  Stuart  Wortley,     167 

Valentine  Blanchard's  Bromo-iodized  Collodion,   16S 

Hockins's  Iodized  Collodion,   169 

Claudet's  Developer,   169 

Instantaneous  Shutters,   169 

CHAPTER  XXIX. 

Negatives  on  Paper,   171 

The  Talbotype  or  Calotype  Process,  '.   171 

To  Sensitize  Calotype  Paper,   171 

Fixing  of  the  Negative,..   172 

Wax-Paper  Process  of  Legray, .   173 

Geoffray's  Process  with  Cerolein  for  taking  Paper  Negatives,   178 

Turpentine  and  Wax  Process  of  Tillard, . ;   179 

Wet.  Paper  Negative  Process  of  Humbert  de  Molard,  "   180 

Improved  Calotype  Process  by  Prichard,   180 

CHAPTER  XXX. 

Printing  on  Plain  Paper,  on  Albumenized  Paper,  on  Arrow-Root  Paper,   182 

Description  of  the  Materials  used  in  Positive  Printing,. ,   183 

Albumen,   184 

Gelatine,   185 

Amylaceous  or  Non-Azotized  Substances,   186 

Starch,    1S6 

Gum- Arabic   1S7 

Chloride  of  Gold,     187 

Nitrate  of  Uranium,   189 

Acetate  of  Soda,  Citrate  of  Soda,  Phosphate  of  Soda,   190 

Carbonate  of  Soda,   190 

Carbonate  of  Lime,   190 

CHAPTER  XXXI. 

Manipulation  of  Positive  Printing,   192 

Preparation  of  Salted  Paper  .  .  192 

Preparation  of  the  Albumenized  Paper,     194 

Preparation  of  Arrow-Root  Paper,   195 

Formula  for  Salting  Solution,   195 

Sensitizing  Bath,   196 

Formula  for  the  Plain  Silver  Solution,   196 

Formula  for  the  Ammonio-nitrate  of  Silver  Solution,   197 

Fuminating  Process,   198 

CHAPTER  XXXII. 

The  Printing  of  Sensitized  Paper,   200 

Toning  of  the  Prints,     201 

Formulas  for  Toning  Solutions,   202 

Fixing  Solution   203 

Self-acting  Photographic  Washing-Machine,    205 

Mounting  of  Photographs,    205 

What  to  do  with  the  Clippings,   207 

Mounting  Stereographs,   207 

CHAPTER  XXXIII. 

Bertrand's  New  Process  for  Positive  Printing,   209 

Glover's  Resinized  Printing  Process,   210 

CHAPTER  XXXIV. 

Printing  by  Development,   212 

Second  Method  of  Printing  by  Development,  with  a  Chloride  and  a  Bromide,..  213 

Third  Method  of  Printing  by  Development,  with  an  Iodide,   2*15 

Formula  for  Salting  Solution,   215 

Method  of  Sensitizing  by  Means  of  Nitrate  of  Uranium,  (The  PROCESS  of  Niepce 

de  Saint  Victor,)   216 


CONTENTS.  Yii 

CHAPTER  XXXV.  PAGB 

The  Card-Picture,   218 

Lenses  for  the  Card-Picture,  219 

Development,   219 

Fixing,  [[  [  [  221 

Printing  of  Card-Pictures,   222 

Vignette  Printing,                       223 

Toning,  Fixing  and  Mounting,  #  •  * '  224 

On  the  Tinting  and  Coloring  of  Photographs,   224 

Colors  used  most  frequently,     225 

Other  indispensable  articles  []  225 

Coloring  of  a  Portrait, . .'  *  225 

Coloring  of  the  Face,  m  226 

Blonde  hair,  chestnut-colored  hair,  black  hair,   227 

Gray  hair,  red  hair,  white  hair,   228 

Blue  drapery,  green  drapery,  red  drapery,  rose-colored  drapery,  brown  drapery,  pink 

drapery,  white  drapery,  yellow  drapery,   229 

Pearl  Gray,   230 

Violet,   230 

Background,   930 

How  to  imitate  Metals,  etc. ,  with  colors,  230,  231 

CHAPTER  XXXVI. 

Dry  Collodion  Process — Dry  Processes,   232 

The  Albumen  Process,   233 

Formula  for  Iodized  Collodion,   233 

Formula  for  Bromo-Iodized  Collodion,   234 

Drying  Process,   235 

Sensitizing  the  Film,   235 

Exposure  in  the  Camera,   236 

Development  of  the  Image,    23T 

Taupenot  Process — Collodion- Albumen  Process,     237 

Preparation  of  the  Class  Plates,   238 

Formula  for  the  Collodion,   238 

Sensitizing  of  the  Taupenot  Plates,   239 

Exposure,-   239 

Development,  *   239 

Fixing  of  the  Taupenot  Plates,   240 

Modified  Albumen  Process,  by  James  Larpey,  •   240 

Modified  Collodio-Albumen  Process,  by  James  Mudd,   241 

Fothergill  Process,   242 

CHAPTER  XXXVII. 

Dr.  Hill  Norris's  Process — Gelatine  Process,   244 

Preservative  Solution,   244 

Tannin  Process  of  Major  Russell,   245 

The  Tannin  and  Honey  Process,   248 

Resin  Process,   249 

Sutton's  Rapid  Dry  Process,   250 

Keene's  Rapid  Dry  Process,   250 

CHAPTER  XXXVIII. 

Printing  of  Transparent  Positives  by  the  Dry  Process,   252 

To  take  copies  of  any  given  size,   253 

Table  for  enlarging  or  diminishing  Photographs,   256 

Application  of  the  preceding  table,   257 

mlcropiiotography  and  macrophotography,   257 

Solar  Microscope,   .  .   257 

How  to  find  the  point  where  the  Lens  is  to  be  placed,     260 

MACROPHOTOGRAPHY,  OR  THE  ART  OF  TAKING  ENLARGED  PHOTOGRAPHS,   262 

The  Negative  for  enlargement,   262 

The  quality  of  the  Negative,   262 

CHAPTER  XXXIX. 

The  Daguerreotype,   268 

First  operation,  or  the  cleaning  and  polishing  of  the  Silvered  Plates,   268 

Second  operation,  or  the  Sensitizing  of  the  Silvered  Plate,   269 

Third  operation,  or  the  exposure  to  light,   269 

Fourth  operation,  or  Developing  by  the  Vapor  of  Mercury,   270 

Fifth  operation,  or  the  Fixing  of  the  developed  Image,   270 

Sixth  operation,  or  the  Toning  with  Gold,   271 


viii 


CONTEXTS. 


CHAPTER  XL. 

Printing  without  tiie  Salts  of  Silver,   272 

Process  with  the  Salts  of  Iron,   272 

Cyanotype,   273 

Crysotype,   273 

process  with  tiie  salts  of  uranium,   273 

Process  for  Red  Pictures,   274 

Process  for  Grekn  Pictures,   274 

Prockss  for  Violet  Pictures,   274 

Process  for  Blue  Pictures,     275 

Carbon  Process,  '.   275 

Pouncy's  Process,   277 

Pouncy's  New  Carbon  Process,   277 

Pkoci  SSes  of  Salmon  and  Garnier,   278 

Fargier's  Process,   280 

Carbon  Processes  with  the  Salts  of  Iron,   281 

Process  with  Sesquichloride  of  Iron  and  Tartaric  Acid,   281 

To  Transfer  the  Carbon  Print  from  Glass  to  Paper,   283 

Printing  directly  on  Paper  by  means  of  the  Sesquichloride  of  Iron  and  Tartaric 

Acid,   285 

Photographic  Engraving,    286 

Engraving  on  the  Daguerreotype  Plate,   286 

Prockss  of  Fizeau,  :   287 

Process  of  Talbot,   288 

asphalto-type  of  nlcephore  nlepc'e,   291 

Etching  on  Glass,   29G 

Negre's  Process  for  Heliographic  Engraving,   296 

Copies  for  the  Engraver  to  work  from,   296 

Photo-Lithography  and  Photo-Zincography,   297 

Asphalto-Photo-Lithographic  Process,   297 

Biciiromo-Photo-Lithographic  Processes  of  Poitevin,   299 

Photo-Typographic  Process  of  Poitevin,  300 

Photo-Lithographic  Process  of  Newton,   300 

Photo-Zincography  by  Colonel  Sir  H.  James,  R.  E. ;  and  Photo-Lithography  by  Mr. 

Osborne,     301 

Photo-Pap yrogr a phy  by  Colonel  Sir  H.  James,  R.  E.,   308 

On  the  production  of  Photographs,  etc.,  on  Glass  in  Enamel  Colors  by  Joubert,.  .  3u8 

CHAPTER  XLI. 

Stereoscopicity,   310 

Strabonic  Stereograph,   316 

"  "   319 

CHAPTER  XLII. 

Celestial  Photography,   320 

CHAPTER  XLIII. 

Heliochromy,  or  the  Art  of  taking  Photographs  in  Natural  Colors,   323 

CHAPTER  XLIV. 

Imperfections  in  Collodion  Negatives  and  Positives  and  their  Remedies,   326 

Fogginess,   326 

Spots  and  Apertures,   328 

Ridges  and  Undulating  Lines,   330 

Streaks  and  Stains,   331 

Feebleness  of  the  Image  or  Deficiency  of  Contrast,   831 

Harshness  or  Excess  of  Contrast,  '   332 

Imperfect  Definition,   332 

Solarization,   332 

Tender  and  Rotten  Films,   332 

Imperfections  in  Paper  Prints,  ,   333 

CHAPTER  XLV. 

Weights  and  Measures,   387 

CHAPTER  XLVI. 

Comparison  of  Theometric  Indications  on  the  Principal  Thermometers  in  use,  340 

CHAPTER  XLVII. 

Comparison  of  Hydrometric  and  Specific  Gravity  Indications,   3-12 

CHAPTER  XLVIII. 

Table  of  the  Elements  of  Matter,  with  their  Symbols  and  Chemical  Equivalents,.  844 


PHOTO  G-RAPHT. 


CHAPTER  I. 

HISTORY  OF  PHOTOGRAPHY. 

Every  step,  whether  thoughtlessly  or  discreetly  taken,  is 
the  commencement  of  a  new  era  in  a  man's  life.  As  in  a 
game  of  chance — where  either  red  or  black  must  occur  at 
the  cessation  of  motion  in  the  finger  of  the  dial-plate — the 
probability  that  red  will  prevail  over  the  black  the  next 
time,  because  black  has  occurred  for  twenty  times  in  succes- 
sion, is  not  valid  ;  it  is  equally  probable  that  black  will  be 
the  successful  color  ;  so,  in  the  game  of  life,  each  successive 
move  is  a  new  beginning  ;  and,  as  a  single  twirl  of  the  rou- 
lette may  be  the  bane  or  the  boon  of  the  career  of  an  indi- 
vidual, so  the  slightest  event,  the  most  insignificant  indeed, 
may  turn  out  to  be  the  center  of  incalculable  results.  New 
developments  in  the  science  of  nature  are  not  limited  to 
their  own  immediate  sphere ;  they  act  and  react  upon  the 
past  and  the  future,  by  illustrating  phenomena  that  before 
were  dark  and  not  understood,  or  by  eliciting  truths  which 
hitherto  were  utterly  unknown.  Thus  it  is  that  the  inven- 
tion of  a  machine,  the  improvement  of  a  part  of  a  machine, 
or  the  discovery  of  some  new  chemical  ingredient,  may  be 
the  date  of  the  commencement  of  a  new  history.  The  verifi- 
cation of  this  idea  is  pertinently  made  manifest  in  the  change 
from  the  simple  double  convex  lens  to  the  achromatic  com- 
bination by  Dolland  ;*  in  the  change  from  the  signal  tele- 
graph on  the  mountains  to  the  electric  telegraph  in  the 
closet ;  in  the  improved  application  of  steam  by  Watt ;  in 
the  development  of  a  picture  on  the  iodized  plates  of  silver 
by  the  vapor  of  mercury;  and  in  the  discovery  of  the  hypo- 

*  Dolland,  J.,  was  bom  in  London,  in  the  year  1706,  and  died  in  1762. 

i* 


10 


HISTORY  OF  PHOTOGRAFIIY. 


sulphite  of  soda,  cyanide  of  potassium,  pyrogallic  acid,  and 
the  protosalts  of  iron.  For  from  the  moment  that  chro- 
matic and  spherical  aberration  could  be  reduced,  the  tele- 
scope and  the  microscope  became  altogether  new  instru- 
ments in  the  hands  of  the  natural  philosopher,  by  which 
many  crude  notions  were  quickly  laid  aside  as  false,  and 
many  new  truths  as  quickly  denuded  of  their  cloudy  habili- 
ments. Astronomy,  one  of  the  oldest  of  sciences — one  whose 
history  can  be  traced  back  to  the  time  of  the  Chaldeans — 
entered,  at  the  time  of  the  introduction  of  the  achromatic 
refracting  telescope,  upon  an  epoch  as  distinct  in  its  history 
as  the  transition  from  the  system  of  Hipparchus  to  that  of 
Copernicus.  At  the  same  time,  too,  Physiology  received  a 
new  impetus,  by  the  deductions  drawn  with  the  aid  of  the 
compound  achromatic  microscope,  so  that  Biology,  since 
then,  is  gradually  becoming  more  and  more  of  a  science. 
By  means  of  the  former  improved  instrument,  our  eyes  are 
permitted  to  revel  amid  the  enchanting  scenes  of  the  starry 
firmament,  by  the  latter  to  scrutinize  the  realms  of  minute 
organisms  of  the  earth,  and  by  both  to  become  acquainted 
with  the  secrets  of  creation.  For  the  investigator  of  nature 
in  the  great  and  the  minute,  this  is  a  new  era  in  the  history 
of  the  world  as  it  exists  and  acts.  In  like  manner  the  age 
of  steam  and  the  telegraph  commenced  a  new  history  in  the 
social  existence  and  actions  of  men.  The  mild  tenets  of  the 
Gospel,  which  would  seem  to  have  no  connection  whatever 
with  the  subject,  have  been  more  powerfully,  more  effica- 
ciously implanted  in  foreign  soils,  by  the  accessory  instru- 
mentality of  these  agents,  than  by  any  preceding  direct 
operations  of  the  missionary  organization  ;  the  superiority 
of  the  race  of  men  that  have  invented  and  that  wield  such 
mighty  instruments  for  weal  and  for  woe,  is  so  distinctly 
marked,  that  admiration  and  awe  have  engendered,  in  the 
minds  of  the  ignorant  and  less  enlightened,  respect  for  the 
creeds  of  religion  and  morality  of  their  superiors.  Co- 
existent with  the  steam-engine  and  the  electric  telegraph, 
and  equally  important  as  these  in  its  influence  on  the  ways 
and  means  of  life,  is  the  art  of  sun-drawing.  It  is  one  of 
the  great  wonders  of  the  phenomena  of  created  matter,  so 
far  eclipsing  the  seven  vaunted  wonders  of  the  world,  that 
these  recede  into  dark  nooks,  like  the  wired  dolls  of  an  au- 
tomatic puppet-show.  This  art,  and  the  science  that  ex- 
plains the  different  effects  produced  in  its  manipulations, 
form  the  subject  of  the  present  volume.  The  art  and  the 
science  are  of  modern  origin  and  of  recent  date. 


HISTORY  OF  PHOTOGRAPHY. 


Sun-drawing,  Heliography,  and  Photography  are  synony- 
mous expressions  for  the  same  phenomenon,  although  ety- 
mologically  the  two  latter  are  somewhat  different — helio- 
graphy signifying  sun-writing,  whilst  the  word  photography 
signifies  light-writing.  Not  one  of  these  expressions  is 
strictly  correct,  because  actinic  impressions  can  be  obtained 
from  rays  emanating  from  the  moon,  from  artificial  light,  or 
the  electric  spark.  Actinic  drawing  would  probably  be  the 
best  name,  although  as  regards  the  representation  of  facts 
by  words,  it  is  immaterial  for  the  masses  of  mankind  whether 
these  words  have  an  intrinsic  or  root-meaning  or  not.  The 
phenomena  comprehended  under  any  one  of  the  above  syn- 
onymous expressions,  depend  immediately  upon  what  is 
termed  light  as  the  force  or  cause,  and  upon  the  property, 
which  only  certain  substances  apparently  possess,  of  being 
affected  according  to  the  intensity  of  the  light  employed. 
The  principal  of  these  substances  are  the  salts  of  silver,  the 
salts  of  iron,  bichromate  of  potassa,  and  certain  resins,  as 
the  oil  of  lavender  and  asphaltum.  That  light  acts  upon  or- 
ganized substances  is  a  phenomenon  which  must  have  been 
observed  by  the  first  occupants  of  earth ;  they  could  not 
fail  to  remark  the  brilliant  hues  on  the  side  of  an  apple  that 
received  the  direct  rays  of  the  sun,  and  to  contrast  these 
resplendent  mixtures  of  red,  crimson,  green,  purple,  yellow, 
orange,  and  other  colors,  on  the  one  side,  with  the  white, 
or  greenish  white,  on  the  side  exposed  simply  to  the  diffused 
light  of  day.  The  variegated  foliage  of  a  tropical  clime,  as 
contrasted  with  the  continual  merging  into  green,  according 
to  the  increase  in  latitude,  gives  evidence  of  the  influence 
of  actinic  action  ;  and  this  change  of  green  into  white  in 
the  leaves  and  stalks  of  similar  plants,  when  supplied  with 
heat  and  air,  and  not  with  light,  is  a  still  stronger  proof  of 
heliographic  influence.  But  this  species  of  influence  is  not 
limited  to  the  vegetable  part  of  the  earth ;  it  is  perceived, 
in  all  its  beauties,  in  the  blooming  cheeks  of  a  maiden  from 
Kaiserstuhl  in  the  Black  Forest,  or  from  the  pasturing  de- 
clivities of  the  Tyrolese  Alps ;  and  its  deficiency  is  quite  as 
apparent  in  the  pale,  white,  and  lifeless  facial  integuments 
of  the  unfortunate  denizens  of  crowded  cities,  as  in  the 
blanched  stalks  of  celery  in  a  dunghill,  or  the  sickly  white 
filiform  shoots  of  potatoes  in  a  dark  cellar.  These  phenom- 
ena are  full  of  wonder,  no  less  so  than  any  of  the  opera- 
tions of  sun-drawing  on  paper  or  collodion,  and  quite  as  in- 
explicable ;  but  they  have  long  failed  to  excite  astonishment, 
from  the  frequency  and  commonness  of  their  occurrence. 


12 


HISTORY  OF  PHOTOGRAPHY. 


The  first  remark  in  reference  to  the  cause  of  the  change 
of  color  in  silver  salts  is  due  to  the  distinguished  Swedish 
cli emist,  Scheele.*  He  regarded  the  blackening  effect  of 
chloride  of  silver,  when  exposed  to  the  rays  of  the  sun,  as 
caused  by  a  species  of  reduction  of  the  salt  to  the  metallic 
state  and  the  accompanying  formation  of  hydrochloric  acid. 
He  undertook  a  course  of  experiments,  to  ascertain  whether 
all  the  colors  of  the  spectrum  had  an  equal  influence  in  col- 
oring or  blackening  this  salt,  and  arrived  at  the  conclusion 
that  the  maximum  chemical  or  decomposing  action  of  the 
spectrum  was  in  the  neighborhood  of  the  violet  part,  and 
that  it  gradually  diminished  toward  the  red,  where  it  was 
scarcely  perceptible.  The  researches  of  Scheele  in  this  track 
terminated  here  ;  and  no  application  of  the  property  of  black- 
ening of  the  chloride  of  silver  to  photogenic  purposes  was 
made  until  after  the  lapse  of  several  years. 

In  1801  Ritterf  not  only  corroborated  the  experiments  of 
Scheele,  but  demonstrated  that  chloride  of  silver  was  black- 
ened to  some  distance  external  to  the  spectrum,  on  the  violet 
side.  The  scientific  investigators  of  the  time  repeated  the 
experiments  without  any  further  developments. 

Dr.  WollastonJ  published  a  report  of  experiments  which 
he  made  with  gum-guaicum,  when  acted  upon  by  the  dif- 
ferent colored  rays  of  the  spectrum.  The  violet  rays  turned 
paper,  stained  yellow  by  a  solution  of  this  gum  in  alcohol, 
to  green,  which  was  soon  changed  back  to  yellow  by  the 
red  rays  ;  he  discovered  afterward,  however,  that  the  heat  of 
the  red  rays  was  sufficient  of  itself  to  reproduce  the  yellow 
color  of  the  tincture  of  the  gum. 

The  same  results  were  obtained  by  Berard.  He  experi- 
mented with  half  the  spectrum  at  a  time,  which  was  con- 
densed by  a  lens  to  a  focus,  and  made  to  impinge  at  this 
point  upon  chloride  of  silver.  The  half  next  the  violet,  or 
more  refrangible  rays,  were  very  efficacious  in  discoloring 
this  salt  of  silver ;  whilst  the  other  half,  or  red  side,  and 
least  refrangible  rays,  although  far  more  luminous,  produced 
no  blackening  effect.  The  experiments  of  Seebeck  seem 
to  show  that  light  transmitted  through  colored  glass  pro- 

*  Scheele,  Charles  William,  was  born  on  the  nineteenth  of  December, 
1742,  at  Stralsund,  Sweden.  He  died  on  the  twenty-first  of  May,  1786,  at 
Koeping,  on  Lake  Moeler. 

f  Ritter,  John  William,  was  born  at  Samitz,  in  Silesia,  in  1776,  and  died 
in  1810. 

\  Wollaston,  William  Hyde,  M.D.,  was  born  on  the  sixth  of  August, 
1766,  at  East-Dereham,  and  died  December  twenty-second,  1828,  in  London. 


HISTORY  OF  PHOTOGRAPHY. 


13 


duced  the  same  general  effect  as  the  different  colored  rajs 
of  the  spectrum.  He  furthermore  ascertained  that  a  piece 
of  paper  dipped  in  a  rather  concentrated  and  neutral  solu- 
tion of  chloride  of  gold,  in  the  dark,  was  not  reduced,  as 
long  as  it  was  kept  in  the  dark;  whereas  if  it  had  previously 
been  exposed  to  the  direct  rays  of  the  sun,  it  gradually 
turned  purple  in  the  dark  chamber.  Sir  Humphry  Davy 
observed  that  the  oxide  of  lead,  in  a  moist  condition,  is  acted 
upon  very  differently  by  the  red  and  the  violet  rays  of  the 
spectrum ;  by  the  latter,  the  puce-colored  oxide  is  turned 
black — by  the  former,  red.  He  ascertained,  too,  that  hy- 
drogen and  chlorine,  when  exposed  to  the  rays  of  the  sun, 
frequently  enter  into  combination  so  vividly  as  to  produce 
an  explosion  in  the  formation  of  hydrochloric  acid  ;  but  the 
two  gases  may  be  kept  in  contact,  in  the  dark,  without  un- 
dergoing much  change.  A  solution  of  chlorine  in  water  re- 
mains unchanged,  as  long  as  it  is  kept  out  of  the  light ;  but 
is  soon  converted  into  hydrochloric  acid,  by  decomposing 
the  water,  when  exposed  to  the  sun.  A  similar  case  of  de- 
composition is  effected  by  light,  when  carbonic  oxide  and 
chlorine  are  exposed  to  light ;  they  then  enter  into  combi- 
nation chemically,  condensing  into  a  substance  denominated 
phosgene  gas. 

The  preceding  remarks  comprehend  the  sum  and  substance 
of  the  knowledge  of  the  chemical  effects  of  light  previous  to 
its  application  to  the  taking  of  impressions  of  pictures  by 
the  salts  of  silver  or  otherwise.  It  is  true  that  a  certain 
Hofrmeister  published  some  vague  remarks  about  the  sun 
being  an  engraver,  several  years  previous  to  Daguerre's 
publication  ;  but  they  were  the  mere  remarks  of  one  who 
probably  thought  the  thing  possible  without  possessing  the 
most  distant  idea  of  the  mode  of  its  effectuation.  And  in 
the  report  which  Arago  made  to  the  Chamber  of  Deputies 
in  reference  to  Daguerre's  discovery,  this  distinguished 
philosopher  mentions  the  name  of  Charles  as  having  been  in 
possession  of  a  process  for  communicating  pictures,  by  the 
aid  of  the  sun,  to  prepared  surfaces.  ISTo  publication  has 
been  discovered  to  corroborate  this  assertion,  and  the  details 
of  the  operation  have  never  been  disclosed. 

The  first  recorded  attempts  by  Wedgwood*  and  Davy,f 
to  take  pictures  by  the  rays  of  the  sun  on  a  prepared  silver 

*  Wedgwood,  Josiah,  was  born  at  Newcastle-under-Lyne,  in  1730,  and  died 
in  the  year  1795. 

f  Sir  Humphry  Davy  was  born  at  Penzance,  in  1778,  and  died  at  Geneva, 
in  1828. 


14 


HISTORY  OF  PHOTOGRAPHY. 


surface,  were  published  in  the  year  1802.  The  receptacle 
of  the  picture  was  either  paper  or  leather,  or  some  other 
convenient  material,  stretched  upon  a  frame,  and  sponged 
over  with  a  solution  of  nitrate  of  silver  ;  over  this  prepared 
surface  a  painting  on  glass  was  placed  in  direct  contact  and 
exposed  to  the  rays  of  the  sun.  It  is  evident  that  the  pic- 
ture thus  obtained  would  be  inverted  as  to  light  and  shade. 
The  difficulty,  which  at  this  time  could  not  be  overcome, 
was  the  fixing  of  the  picture ;  and  the  process  was  aban- 
doned on  this  account.  No  chemical  substance  was  known 
whose  peculiar  properties  were  of  such  a  nature  as  to  dissolve 
the  unaltered  salt  of  silver  and  leave  the  portions  on  which 
the  image  was  projected  untouched  or  uninjured.  These  ex- 
periments of  Wedgwood  were  actually  made  several  years 
previous  to  the  publication  in  1802  ;  because  at  that  date  he 
had  been  dead  for  seven  years.  The  surface  prepared  with 
nitrate  of  silver  was  not  sensitive  enough  to  receive  an  im- 
pression in  the  camera  obscura,  although  Sir  Humphry  Davy 
succeeded  in  getting  a  very  faint  image  in  the  solar  micro- 
scope, where  the  picture  was  very  much  condensed  in  size  or 
situated  very  near  the  focus  of  parallel  rays.  From  that  date 
to  the  year  1814  not  only  no  other  publication  appeared,  but 
there  are  no  accounts  of  any  one  having  prosecuted  the  study 
of  sun-drawing.  At  this  time  a  new  laborer  entered  the  field 
of  investigation  and  directed  all  his  mental  energies  to  the 
discovery  of  means  of  making  sun-pictures.  From  the  work 
of  Daguerre,  which  was  published  several  years  later,  it  ap- 
pears that  Niepce*  was  the  first  who  obtained  a  permanent 
sun-picture  ;  to  him  we  are  indebted  for  the  first  idea  of  a 
fixing  material ;  it  was  he  who  first  employed  silver  and 
the  vapor  of  iodine.  The  process  of  Niepce  had  been  so  far 
perfected  as  to  admit  the  use  of  the  camera,  which,  by 
reason  of  the  want  of  sensitiveness  in  the  materials  used., 
had  remained  a  useless  optical  arrangement,  is  icpee,  in  his 
experiments,  discarded  the  use  of  the  silver  salts,  and  sub- 
stituted in  their  place  a  resinous  substance  denominated  the 
"  Bitumen  of  Judaea."  He  named  his  process  "  Heliogra- 
phy,"  or  "  Sun-drawing."  His  pictures  were  produced  by 
coating  a  metal  plate  with  the  resinous  substance  above 
alluded  to,  and  then  exposing  this  plate,  under  a  picture  on 
glass,  or  in  the  camera,  for  several  hours  in  front  of  the  ob- 
ject to  be  copied.    By  this  exposure  to  light  the  parts  of 

*  Niepce,  Joscph-Nicepliore,  wa3  born  at  Chalon-sur-Saone,  and  died  in 
1833, 


HISTORY  OF  PHOTOGRAPHY. 


15 


the  bitumen  which  had  been  acted  upon  by  the  rays  under- 
went a  change  according  to  the  actinic  intensity,  whereby 
they  became  insoluble  in  certain  essential  oils.  By  treat- 
ment afterward  with  these  essences,  as,  for  instance,  the  oil 
of  lavender,  the  picture  was  developed,  the  shadows  being 
formed  by  the  brilliant  surface  of  the  metal  exposed,  by 
the  solvent  action  of  the  essential  oil  in  those  parts  of 
the  resin  on  which  the  rays  of  light  had  not  impinged  ; 
whilst  the  lights  were  represented  by  the  thin  film  of 
bitumen  wdrich  had  become  altered  and  insoluble  in  the 
oleaginous  substance  employed  in  fixing.  Some  of  the 
specimens  produced  by  this  method  at  this  j>eriod  exist  still 
in  the  British  Museum ;  some  of  them  are  in  the  form  of 
etchings,  having  been  acted  upon  probably  by  the  galvanic 
current.  It  is  evident  that  Niepce  was  acquainted  with  a 
method  of  fixing  his  sun-drawings  ;  but  his  successes  were 
limited  to  productions  which  now  would  be  regarded  very 
trivial  and  unsatisfactory.  After  ten  years'  labor  in  the 
prosecution  of  his  favorite  investigation,  by  some  accidental 
disclosure,  ISTiepce  became  acquainted  with  Daguerre,*  who 
had  been  experimenting  independently  in  the  same  path. 
Daguerre's  experiments  with  chemical  processes  and  the 
camera  date  from  the  year  1824  ;  and  in  1829  these  two 
great  originators  of  sun-drawings  entered  into  partnership 
for  mutually  investigating  this  enchanting  art.  In  1827 
Mepce  had  presented  an  article  to  the  Royal  Society  of 
London  on  this  subject ;  but  as  yet  Daguerre  had  not  ar- 
rived at  any  successful  results,  nor  had  he  published  any 
thing  in  reference  to  them.  The  process  of  Daguerre  aimed 
to  perform  the  same  operation  by  the  same  method,  that  is, 
by  light ;  the  materials  for  the  sensitive  surface,  for  devel- 
oping and  fixing  alone,  being  different.  In  this  process  are 
found  the  use  of  the  camera,  iodide  of  silver  on  a  metal 
plate,  mercury  as  a  developer,  and  hyposulphite  of  soda  as  a 
fixing  agent ;  in  that  of  Niepce,  bitumen  on  a  metal  plate, 
iodine  as  a  developer,  and  oil  of  lavender  in  place  of  the 
hyposulphite  of  soda.  The  use  of  the  latter  substance  was 
probably  suggested  to  Daguerre  by  the  publication  of  a 
paper,  by  Sir  John  Herschel,  on  the  solubility  in  this  men- 
struum of  the  insoluble  salts  of  silver.  The  image  formed 
on  the  iodized  surface  was  quite  latent  until  brought  out  by 
the  vapor  of  mercury.  It  seems  wonderful  how  Daguerre 
should  hit  upon  the  idea  of  using  this  vapor,  or  that  a  latent 


*  Daguerre,  L.  J.  M.,  was  born  at  Cormeilles,  in  1787,  and  died  in  1851. 


16 


HISTORY  OF  PHOTOGRAPHY. 


image  was  on  the  surface.  Knowing  the  latter  and  the 
possibility  of  snch  a  development,  the  chemist  has  only  to 
persevere  in  a  systematic  exploration  among  the  infinite 
number  of  chemical  substances,  in  order  finally  to  meet  with 
success  ;  but  Daguerre  could  not  a  priori  be  furnished  with 
such  positive  knowledge  ;  hence  our^admiration  at  his  suc- 
cess, at  the  hardihood  and  perseverance  of  his  character  in 
search  of  this  success,  can  not  be  otherwise  than  boundless. 
Niepce,  too,  is  entitled  to  an  equal  share  of  honor ;  for 
without  Niepce,  in  all  probability,  sun-drawing  would  still 
be  a  latent  property  of  nature  ;  as  also,  without  Daguerre, 
the  discoveries  of  Niepce  would  not  stand  out  in  that  bold 
relief  in  which  they  are  now  exhibited. 

The  plates  which  Daguerre  used  for  the  reception  of  the 
heliographic  image  were  of  silver,  or  of  copper  plated 
with  silver.  The  silver  surface,  highly  polished,  was  sub- 
jected to  the  vapor  of  iodine  in  the  dark-chamber;  the 
iodide  of  silver  thus  formed  being  very  sensitive  to  the 
actinic  influence,  the  plate  was  ready  for  the  reception  of 
the  latent  image.  This  mode  of  sensitizing  the  surface 
had  reduced  the  time  of  exposure  from  hours  to  minutes; 
and  an  increase  of  sensitiveness  was  attained  at  the  sug- 
gestion of  Fizeau,  who  recommended  the  use  of  bromine- 
water  ;  and  about  the  same  time  the  chloride  of  iodine 
was  recommended  as  an  accelerator  by  Claudet ;  and  the 
bromide  of  iodine  by  Gaudin.  By  means  of  these  ac- 
celerators the  time  was  again  reduced  from  minutes  to 
seconds.  In  this  state  of  perfection  we  will  now  leave  the 
art  of  heliography,  or  of  the  Daguerreotype  as  it  is  more 
frequently  denominated,  and  observe  only,  in  conclusion,  that 
this  discovery  of  Daguerre  was  reported  to  the  world  in 
January,  1839 ;  but  the  process  was  not  communicated  until 
after  a  bill  had  been  passed  by  the  French  government, 
which  secured  to  Daguerre  a  pension  of  six  thousand  francs 
a  year,  and  to  Isidore  Niepce,  the  son  of  Daguerre's  part- 
ner, an  annual  pension  for  life  of  four  thousand  francs,  one 
half  of  which  was  to  revert  to  their  widows. 

That  Mr.  Fox  Talbot  was  acquainted  with  the  experi- 
ments of  Niepce  and  Daguerre  is  very  doubtful,  because  the 
result  of  these  experiments  was  kept  secret  until  the  pen- 
sions had  been  granted  ;  but  Mr.  Talbot  states,  in  the  com- 
munication which  he  made  to  the  Royal  Society  on  the 
thirty-first  of  January,  1839,  six  months  before  the  publica- 
tion of  Daguerre's  process,  that  he  had  been  applying  the 
property  of  discoloration  of  the  silver  salts  by  light  to  use- 


HISTORY  OF  PHOTOGRAPHY. 


11 


ful  purposes.  This  application  consisted  in  preparing  a  sen- 
sitive paper  for  the  copying  of  drawings  or  paintings,  by 
direct  contact.  The  paper  was  clipped,  in  the  first  place,  in  a 
solution  of  chloride  of  sodium,  and  afterward  in  one  of 
nitrate  of  silver,  whereby  a  film  of  chloride  of  silver  was 
formed  —  a  substance  much  more  sensitive  to  light  than 
the  nitrate  of  silver,  which  had  heretofore  been  employed 
for  photographic  purposes.  The  object  to  be  copied,  which 
had  to  be  transparent,  or  partly  so,  was  applied  in  direct 
contact  with  the  sensitive  paper,  and  exposed  to  the  rays  of 
the  sun.  By  this  means,  a  copy  of  the  object  was  obtained, 
in  which  the  lights  and  shades  were  inverted.  This  was 
the  negative,  which,  when  fixed,  was  superimposed  on  an- 
other piece  of  the  sensitive  paper,  and  exposed  in  its  turn  to 
the  rays  of  light,  whereby  a  positive  print  was  obtained  of 
the  object,  in  which  the  lights  and  shades  were  exhibited  in 
their  natural  position. 

The  communication  of  Talbot  is  the  first,  which  laid  the 
foundation  of  multiplying  copies  of  a  picture  by  the  com- 
bined action  of  light  and  chemical  material ;  it  gave  the 
first  idea  of  photographic  printing. 

In  the  year  1841  another  method  was  devised  and  pa- 
tented, called  Talbotype  or  Calotype,  The  process  con- 
sisted in  preparing  paper  with  the  iodide  of  silver,  which, 
when  exposed  to  light,  became  the  recipient  of  a  latent 
image,  which  afterward  was  made  to  appear  by  the  applica- 
tion of  a  developer,  and  was  fixed  with  hyposulphite  of 
soda.  This  method  is  the  essential  point  in  the  present  col- 
lodion process ;  it  is,  in  fact,  the  very  foundation  of  photo- 
graphy. Talbot,  therefore,  merits  an  equal  position  in  his- 
tory with  Niepce  and  Daguerre.  These  three — this  much 
to  be  honored  trio — are  the  undisputed  originators  of  that 
branch  of  natural  science  which  hereafter  will  occupy  a 
prominent  part  of  human  intelligence. 

The  paper,  in  the  Calotype  process,  was  immersed  in  a 
solution  of  iodide  of  potassium,  <5r  floated  on  its  surface  ;  as 
soon  as  dry,  it  was  floated  on  a  solution  of  nitrate  of  silver 
for  a  certain  time.  By  this  operation,  a  film  of  iodide  of 
silver  was  formed  by  the  double  decomposition  of  the  two 
salts  in  contact.  The  excess  of  iodide  of  potassium,  or  of 
nitrate  of  silver  and  the  nitrate  of  potassa  were  afterward 
removed  by  washing  in  several  waters.  These  operations 
had  to  be  performed  in  the  dark  chamber,  by  the  aid  of  a 
small  candle  or  lamp.  When  the  paper  was  required  to  be 
used,  it  was  brushed  over  with  a  solution  of  one  part  of 


13 


HISTORY  OF  PHOTOGRAPHY. 


nitrate  of  silver,  containing  fifty  grains  to  the  ounce,  two 
parts  of  glacial  acetic  acid,  and  three  of  a  saturated  solution 
of  gallic  acid  ;  or  the  paper  was  floated  on  the  surface  of 
this  gallo-nitrate  of  silver,  as  it  is  called,  for  a  few  seconds, 
and  the  excess  of  fluid  removed  by  blotting-paper.  By  this 
mode  of  treatment,  the  paper  was  rendered  very  sensitive, 
sufficiently  so  to  receive  an  impression  of  a  living  person,  by 
means  of  the  camera  obscura.  An  exposure  of  one  second, 
or  of  a  fraction  of  a  second,  was  found  effective  in  produc- 
ing an  impression  on  the  Calotype  paper.  This  impression 
might  be  totally  invisible,  partly  visible,  or  distinctly  visible, 
according  to  the  circumstances  of  time,  intensity  of  the 
light,  and  sensitiveness  of  the  prepared  paper.  The  latent 
image,  or  partially  visible  image,  was  then  developed  to  any 
degree  of  depth  of  shades,  by  washing  the  surface  of  the 
paper  with  one  part  of  a  solution  of  nitrate  of  silver,  of  the 
same  strength  as  before,  and  four  parts  of  the  saturated  so- 
lution of  gallic  acid.  The  image  gradually  becomes  devel- 
oped by  this  treatment,  and  in  a  few  minutes  reaches  its 
maximum  degree  of  intensity.  The  fixing  solutions  were 
bromide  of  potassium  and  hyposulphite  of  soda.  The  first 
impression,  thus  obtained,  was  in  this  process,  as  well  as  in 
that  with  chloride  of  silver,  a  negative,  which,  by  continu- 
ing the  process  and  using  this  negative  as  an  original  object, 
either  in  the  camera  or  by  direct  application,  produced  a 
positive,  with  the  lights  and  shades  in  their  appropriate 
positions. 

The  difficulty  in  this  process  is  the  want  of  homogeneity, 
and  of  a  sufficient  transparency,  in  the  structure  of  paper. 
The  want  of  transparency  probably  was  regarded  the  great- 
est drawback  in  the  production  of  negatives  ;  whilst  the  ir- 
regularities in  the  fiber  of  the  paper  could  never  yield  a  sur- 
face to  compete  with  the  brilliant  and  even  surface  of  a 
polished  piece  of  silver  for  the  reception  of  positive  pictures. 
To  obviate  these  disadvantages,  Sir  John  Herschel  proposed 
the  use  of  glass  plates,  and  was  the  first  to  employ  them. 

In  the  year  1847  Niepce  de  St.  Victor,  the  nephew  of 
Daguerre's  partner,  to  whom  we  are  indebted  for  many  in- 
teresting publications  on  the  Chromotype,  managed  to  fix  a 
film  of  albumen  on  the  glass  plates.  This  film  is  intimately 
mixed  with  the  iodides  or  bromides,  and  flowed  upon  the 
surface  of  the  glass.  Such  albumen  plates  are  employed  by 
many  very  distinguished  artists  at  the  present  day,  who  ex- 
hibit specimens  of  fine  and  sharp  definition  and  softness  of 
tone  in  their  stereographs,  that  have  not  been  surpassed  by 


HISTORY  OF  PHOTOGRAPHY. 


19 


any  other  process ;  as,  for  instance,  regard  those  beautiful 
productions  of  Ferrier. 

The  next  important  improvement  in  photography  was  ef- 
fected in  1851 ;  it  is  the  foundation-stone  of  a  new  era.  Le- 
o-ray originally  suggested  that  collodion  might  be  used  as 
the  receptacle  of  the  sensitive  material,  in  place  of  albumen  ; 
but  we  are  indebted  to  Archer  for  the  practical  application 
of  the  solution  of  gun-cotton,  and  of  the  mode  of  employ- 
ment, pretty  much  as  it  now  stands.  Archer  substituted pyro- 
gallic  acid  for  the  gallic  acid  that  had  been  previously  used 
in  the  development  of  the  latent  image.  Pyrogallic  acid, 
although  still  used  as  a  developer,  has  been  since  pushed 
aside,  in  a  great  measure,  by  another  substitute,  the  sulphate 
of  the  protoxide  of  iron,  at  the  suggestion  of  Talbot.  It  is 
now  limited  principally  to  the  operation  of  intensifying. 

Collodion  is  a  solution  of  a  substance  very  much  resem- 
bling gun-cotton  in  ether  and  alcohol.  A  decided  improve- 
ment, in  many  respects,  has  been  made  in  this  solution,  at 
the  suggestion  of  Sutton,  the  editor  of  the  Photographic 
Notes,  who  recommends  an  excess  of  alcohol.  When  this 
solution  is  poured  upon  a  piece  of  clean  glass,  it  forms  a 
very  thin,  even,  and  transparent  film,  which  quickly  dries, 
and  can  scarcely  be  distinguished  from  the  surface  of  the 
glass  beneath  it.  It  contains  the  materials  for  sensitization. 
The  discovery  and  application  of  this  substance  have  given 
rise  to  what  is  denominated  the  collodion  process.  It  is  im- 
possible to  calculate  the  impetus  given  to  photography  by 
this  discovery,  or  its  value  to  society,  in  the  promotion  of 
comfort  and  happiness ;  much  less  can  an  idea  be  conceived 
of  the  resources  to  which  it  may  give  rise  by  its  future  de- 
velopments. 

In  the  year  1838  or  1839,  Mr.  Mungo  Ponton  pointed  out 
a  very  important  discovery  in  reference  to  bichromate  of 
potassa,  when  acted  upon  by  light,  whereby  this  salt,  the 
chromic  acid,  or  (as  Mr.  Talbot  advances)  the  organic  mat- 
ter with  which  the  salt  is  in  combination,  becomes  insoluble. 
The  paper  for  experimenting  on  this  point  is  uniformly  coated 
with  a  mixture  of  bichromate  of  potassa,  gelatine,  and  lamp- 
black in  cold  distilled  water,  and  allowed  to  dry  in  the  dark 
room.  When  dry,  it  is  ready  to  be  placed  beneath  a  nega- 
tive. The  time  varies  from  four  or  five  minutes  to  a  quarter 
of  an  hour  or  upward.  The  impression  obtained  in  this 
w^ay  is  quite  latent,  and  is  made  to  appear  by  dissolving  off, 
with  hot  water,  those  parts  that  have  been  entirely  or  par- 
tially excluded  from  the  actinic  influence  of  the  light.  The 


20 


HISTORY  OF  PHOTOGRAPHY. 


picture  resulting  from  this  treatment  is  a  positive  print,  in 
black  and  white,  of  which  the  shades  are  produced  by  the 
carbon  of  the  lampblack.  This  discovery  gave  rise  to  car- 
bon-printing. 

In  the  year  1852  a  patent  was  taken  out  in  England  by 
Talbot,  reserving  to  himself  the  sole  use  of  bichromate  of 
potassa  and  gelatine  in  the  production  of  photo-engravings 
on  steel.  Three  years  after  this  date,  that  is,  in  1855, 
Poitevin  patented  a  process  for  making  carbon  prints  by 
means  of  the  same  materials  combined  with  coloring  matter, 
as  well  as  for  obtaining  a  photographic  image  on  a  litho- 
graphic stone,  capable  of  being  printed  from  by  the  ordinary 
lithographic  press.  In  Talbot's  process  the  steel  plates  were 
covered  with  a  coating  of  bichromate  of  potash  and  gelatine, 
the  operation  taking  place  in  the  dark  chamber.  A  trans- 
parent positive  is  then  placed  on  its  surface,  and  the  plate  is 
then  exposed  to  the  light.  The  latent  image  is  developed 
as  before  alluded  to.  Afterward  the  edges  of  the  plate  are 
raised  with  wax,  or  some  resinous  preparation,  so  as  to  form 
a  sort  of  dish,  into  which  is  poured  the  acid  or  etching-fluid, 
which  etches  away  the  parts  exposed  by  the  removal  of  the 
soluble  gelatine.  The  etching-fluid  used  by  Talbot  was  the 
bichloride  of  platinum.  Poitevin's  process  is  in  principle 
the  same.  The  disadvantage  in  the  latter  process  arises 
from  the  want  of  durability  in  the  image,  which,  being 
formed  out  of  organic  matter  lying,  as  it  must  do,  between 
the  ink  and  the  stone,  is  liable  to  be  soon  abraded  after  a 
few  pictures  have  been  printed  from  it.  These  attempts 
have  created  a  number  of  improvements,  by  which  matrixes 
can  now  be  furnished,  by  the  aid  of  photography,  for  the 
engraver's  press,  the  lithographic  press,  and  the  typographic 
press. 

Messrs.  Cutting  and  Bradford  took  a  patent  out,  in  this 
country,  for  a  process  in  which  the  image  is  formed  directly 
of  greasy  ink  used  in  lithography. 

The  next  important  step  in  photo-lithography  is  that  in 
which  the  picture  is  first  formed  by  bichromate  of  potash 
and  gelatine  on  lithographic  transfer-psapei^  that  is,  paper 
coated  with  a  layer  of  albumen.  A  negative  is  placed  m 
direct  contact  with  paper  so  prepared,  from  which  an  image 
is  obtained,  that  is,  after  certain  other  operations,  transferred 
directly,  in  lithographic  ink,  to  the  stone.  This  process  was 
patented  in  1859,  at  Melbourne,  in  Australia,  by  Mr.  Osborne, 
for  which  he  was  awarded  by  the  government  of  the  colony 
of  Victoria  the  sum  of  one  thousand  pounds.    This  process 


HISTORY  OF  PHOTOGRAPHY. 


21 


promises  to  be  the  basis  of  the  most  successful  operations  in 
photo-lithography. 

Asser,  of  Amsterdam,  invented  or  used  the  transfer  pro- 
cess at  the  same  time  that  Osborne  was  using  it  in  Aus- 
tralia. 

Colonel  Sir  Henry  James  makes  use  of  zinc,  upon  which 
he  transfers  the  image  formed  in  ink ;  the  image  having  been 
produced  on  engraver's  tracing-paper  by  the  means  adopted 
by  Talbot,  Poitevin,  and  Osborne. 

In  the  year  1859  another  process  for  photo-lithographic 
purposes  was  patented  in  Vienna,  in  Austria,  in  wilich  as- 
phaltum is  again  brought  into  the  field.  The  developer  is 
oil  of  turpentine  and  water.  The  latent  image  is  produced 
in  a  film  consisting  of  a  solution  of  asphaltum  in  chloroform, 
by  means  of  a  collodion  negative  exposed  for  a  number  of 
hours.  As  soon  as  the  soluble  asphaltum  has  been  removed, 
the  remaining  insoluble  parts  which  form  the  shades  of  the 
image  are  coated  with  a  layer  of  ink  by  the  printer ;  the 
image  is  then  gummed  in,  and  slightly  etched ;  after  which 
it  is  ready  for  the  press. 

Poitevin  has  just  published  a  new  method  of  direct  car- 
bon-printing on  paper.  It  depends  upon  the  insolubility 
communicated  to  certain  organic  matters,  such  as  gum,  al- 
bumen, gelatine,  etc.,  by  the  per-salts  of  iron,  and  on  a  new 
fact  observed  by  him,  namely,  that  this  matter,  coagulated 
and  rendered  insoluble  in  cold  and  even  in  hot  water,  be- 
comes soluble  under  the  influence  of  light,  and  in  contact 
with  tartaric  acid,  which,  by  the  reduction  of  the  iron  salt, 
restores  to  the  organic  matter  its  natural  solubility.  The 
paper  for  carbon-printing  is  floated  in  a  bath  of  gelatine 
dissolved  in  water  and  colored  with  a  sufficient  quantity  of 
lampblack,  or  other  coloring  matter,  and  maintained  at  a 
lukewarm  temperature.  The  paper  becomes  thus  uniformly 
covered  with  the  colored  gelatine. 

The  sensitizing  part  is  performed  in  the  dark  room  by 
plunging  each  sheet  into  a  solution  of  sesqui  chloride  of  iron 
and  tartaric  acid  in  water.  By  this  immersion  the  gelatine 
becomes  quite  insoluble  even  in  boiling  water.  The  sheets 
are  taken  out  and  dried.  The  prints  are  obtained  by  placing 
transparent  positives  in  direct  contact  with  the  paper  in  the 
printing-frame.  Two  or  three  minutes'  exposure  to  the  rays 
of  the  sun  will  be  found  sufficient  to  render  those  parts 
through  which  the  light  has  passed  soluble  in  boiling  water, 
which  is  the  developer  and  fixing  agent  at  the  same  time. 
A  little  acid  water  is  used  toward  the  end  of  the  washing,  in 
order  to  remove  all  traces  of  the  ferruginous  compound. 


22 


HISTORY  OF  PHOTOGKAPIIY. 


Poitevin  has  other  methods  of  producing  direct  carbon- 
prints,  which,  together  with  this  and  others  preceding,  will 
be  fully  discussed  in  their  proper  place. 

Niepce  de  St.  Victor  has  long  been  experimenting  in  his 
favorite  study  of  the  chromotype.  lie  has  succeeded  in  pro- 
ducing photogenic  impressions  endowed  with  certain  colors 
of  the  original.  Yellow  is  found  very  difficult  to  transfer  to 
the  heliochromic  plate  at  the  same  time  with  other  colors, 
lied,  green,  and  blue,  it  appears,  could  be  formerly  repro- 
duced satisfactorily.  In  the  fifth  memoir  of  Niepce  on  this 
subject,  the  author  states  that  he  can  now  reproduce  yellow 
along  with  other  colors  in  a  definite  manner.  The  trouble 
with  these  heliochromic  specimens  is.  still  their  want  of  per- 
manence. At  the  very  most,  the  colors  can  not  be  preserved 
longer  than  two  or  three  days.  The  problem  to  be  settled 
is  the  means  and  mode  of  fixation. 


CHAPTER  IT. 


PRELIMINARY  OBSERVATIONS. 

The  art  of  Photography  comprehends  all  the  operations 
of  taking  a  picture  on  a  sensitive  surface  by  means  of  light 
and  chemical  reagents.  These  operations  are  as  varied  as 
the  different  substances  on  which  they  are  taken,  or  by 
which  they  are  taken.  In  all  cases,  whatever  may  be  the 
process,  the  conditions  required  in  the  operation  of  pro- 
ducing a  photographic  image  are,  firstly,  a  suitable  ground- 
work or  receptacle,  such  as  paper,  metal,  glass,  or  stone ; 
secondly,  a  coating  of  substances  called  sensitizers,  which 
are  very  sensitively  affected  by  light  and  altered  according 
to  its  intensity ;  thirdly,  chemical  ingredients,  denominated 
developers,  that  act  differently  upon  the  parts  that  have 
been  changed  by  light  from  what  it  does  upon  the  parts 
upon  which  light  has  not  acted  at  all  or  feebly ;  fourthly, 
fixing  agents  or  chemical  solvents  of  the  sensitizing  agents 
that  have  not  been  changed  by  light.  Other  important  con- 
ditions are  comprehended  in  the  light,  requiring  it  to  be  of 
a  certain  intensity,  in  a  certain  direction,  and  in  a  certain 
quantity. 

The  various  sorts  of  matter  for  the  reception  of  the  pho- 
tographic image  have  given  rise  to  a  variety  of  processes, 
whose  appellations  refer  rather  to  the  material  employed 
than  to  any  difference  in  the  actinic  principle ;  thus,  on 
paper,  exist  a  number  of  so-called  processes,  as,  for  instance, 
printing  by  direct  contact,  and  printing  by  development ; 
the  plain-paper  process,  the  wax-paper  process,  the  resin 
process,  and  the  albumen  process.  On  glass  are  found  the 
negative  process,  the  positive  or  ambrotype  process,  and  the 
transfer  process.  On  metal  the  melainotype  and  daguerreo- 
type processes  and  photo-engraving ;  and  on  stone,  photo- 
lithography. In  addition  to  these  may  be  mentioned  the 
card-picture  process  and  that  of  the  stereograph.  In  refer- 
ence to  the  materials  used  in  the  sensitized  photographic 
film,  or  rather  to  contain  the  sensitizing  ingredients,  stand 


24 


PRELIMINARY  OBSERVATIONS. 


out  most  prominently ;  the  Collodion  processes,  wet  and  dry, 
the  Tannin  process,  and  the  Albumen  process. 

The  sensitizing  substances  most  generally  used  are  the 
salts  of  silver  in  combination  with  organic  matter.  In  the 
carbon  process,  as  also  in  photo-lithography,  photo-engrav- 
ing, photo-zincography,  and  photo-glyphography,  the  sensitive 
materials  are  gelatinous  or  resinous  substances  in  combina- 
tion with  certain  chemical  reagents  that  render  them  insolu- 
ble, and  in  which  the  solubility,  in  certain  menstrua,  is  again 
restored  by  the  agency  of  light.  The  salts  that  have  hitherto 
been  used  are  the  bichromate  of  potassa  and  the  sesqui-salts 
of  iron ;  the  receptacles,  asphalt  urn  and  gelatine  ;  and  the 
solvents,  hot  water,  oil  of  turpentine,  and  oil  of  lavender. 
The  fixing  agents  or  solvents  of  the  undecomposed  iodides, 
bromides,  and  chlorides  of  silver  in  the  collodion,  albumen, 
or  surface-sensitized  film,  on  which  the  rays  of  light,  have 
not  acted,  or  but  partially  acted,  are  hyposulphite  of  soda, 
cyanide  of  potassium  and  sulphocyanide  of  ammonium.  The 
chemical  reagents  that  either  develop  the  latent  image  or 
perfect  that  which  light  has  already  commenced,  are  the 
proto-salts  of  iron,  ammonia,  gallic  and  pyrogallic  acid, 
formic  acid,  and,  in  the  daguerreotype-plate,  mercury. 
Other  materials  are  used  in  addition  to  intensify  the  image 
already  formed  by  the  ordinary  developers.  The  principle 
involved  in  the  strengthening  of  negatives  is,  first,  probably 
by  certain  electrical  decompositions,  to  produce  a  deposit 
on  the  shadows  formed  by  means  of  silver,  mercury,  lead,  or 
iodine  ;  and  secondly,  to  blacken  this  deposit  by  sulphuriz- 
ing or  reducing  agents,  or  by  the  alkalies. 

The  great  divisions  into  which  photographic  operations 
may  be  divided  are  those  which  treat  of  negatives  and  posi- 
tives. A  negative  is  an  actinic  impression  on  glass  or  waxed 
paper,  in  which  the  lights  and  shadows  are  inverted,  as  also 
the  figures  and  the  different  items  that  form  the  picture  ; 
that  is,  right  becomes  left,  and  left  right.  The  negative  is 
the  matrix  from  which  photographic  prints  are  obtained 
either  on  paper  or  other  material ;  these  prints  are  produced 
either  by  direct  contact  of  the  paper  or  glass  with  the  nega- 
tive, or  the  negative  is  placed  in  one  focus  of  a  camera,  and 
the  paper  or  glass  in  its  conjugate  focus.  Such  prints  or 
impressions,  whether  by  reflected  or  transmitted  rays,  are 
positives,  in  which  the  lights  and  shades,  as  well  as  all  the 
delineations,  are  in  their  true  and  natural  position.  There 
is  another  class  of  positives  in  which  the  shading  is  natural, 
but  the  delineations  are  inverted ;  these  are  exemplified  in 


PRELIMINARY  OBSERVATIONS. 


25 


the  daguerreotype,  ambrotype,  and  melainotype,  which  are 
exhibited  only  by  reflected  light. 

As  the  present  work  is  intended  for  practical  men,  it  will 
be  necessary  at  the  very  outset  to  give  a  list  of  all  the  arti- 
cles and  arrangements  required  in  the  successful  pursuit  of 
the  photographic  art. 

LIST  OF  A  PHOTOGRAPHIC  OUTFIT. 

1.  Glass-house,  or  room  in  the  garret  furnished  with  a 
sky-light. 

2.  Dark  room,  for  sensitizing  plates  or  papers. 

3.  Operating  room,  for  collodionizing  plates,  mounting 
prints,  etc. 

4.  Screens  (white,  gray,  blue,  and  artistic)  for  the  glass- 
house. 

5.  Lenses,  (£,  i,  f,  etc.,  stereoscopic  and  orthoscopic.) 

6.  Cameras,  (for  portraits,  views,  stereographs,  and  for 
copying.) 

7.  Ornamental  carpets,  chairs,  stands,  curtains,  pillars, 
balustrades,  etc. 

8.  Head-rests,  etc.,  camera-stands,  mirrors,  brushes,  combs, 
pins,  needle,  and  thread. 

9.  Washhand-stand,  pitcher  and  basin,  soap  and  towels, 
clothes-brush  and  nail-brush. 

10.  Stove,  tongs,  shovel,  poker,  coal  or  wood-box. 

1 1 .  Antechamber,  suitably  furnished  with  lounges,  etc. 

12.  Show-cases  for  artistic  productions,  and  cases  for 
chemicals,  etc. 

13.  Collodion,  (negative  and  positive,)  acetic  acid,  nitric 
acid,  citric  acid,  tartaric  acid,  protosulphate  of  iron,  gallic 
acid,  pyrogallic  acid,  formic  acid,  carbonate  of  soda,  car- 
bonate of  lime,  (chalk,)  chlorinetted  lime,  nitrate  of  silver, 
citrate  of  soda,  phosphate  of  soda,  blue  litmus-paper,  red 
litmus-paper,  sulphide  of  potassium,  sulphocyanide  of  am- 
monium, ammonia,  oxide  of  silver,  iodide  of  potassium, 
iodide  of  ammonium,  iodide  of  cadmium,  iodine,  tincture  of 
iodine,  bromide  of  potassium,  bromide  of  ammonium,  bro- 
mide of  cadmium,  bromine,  nitrate  of  uranium,  bichloride 
of  mercury,  gum-arabic,  starch,  gelatine,  glue,  shellac, 
chloride  of  gold,  acetate  of  soda,  alcohol,  ether,  distilled 
water,  loaf-sugar,  cyanide  of  potassium,  hyposulphite  of 
soda,  pyroxyline,  sulphuric?  acid,  rotten-stone,  tannin,  sesqui- 
chloride  of  iron,  oxalic  acid,  varnish,  hydrochloric  acid, 
acetate  of  lead,  caustic  potassa,  salts  of  tartar,  chloride  of 
sodium,  chloride  of  ammonium,  bichromate  of  potassa,  as- 

2 


26 


PRELIMINARY  OBSERVATIONS. 


phaltum,  copal,  chloroform,  cotton,  nitroglucose,  mastic, 
resin,  thus,  benzoin,  benzine,  wax. 

14.  Funnels,  filtering-stands,  collodion-glasses,  developing 
and  fixing-glasses,  porcelain  or  photographic-ware  baths  and 
dishes,  filtering-paper,  plain  paper,  plain-salted  paper,  albu- 
men paper,  arrowroot  paper,  tinted  paper,  resinized  paper, 
wax  paper,  blotting  paper,  plate-cleaners,  plate-holclers,  Can- 
ton flannel,  cotton  cloths,  silk  cloths,  brushes,  colors,  pencils, 
scale  and  compasses,  magnify  ing-glass,  cases,  mats,  preserv- 
ers, glass  plates  of  various  sizes,  (transparent  and  ground,) 
melainotype-plates,  black  leather,  black  velvet,  black  var- 
nish, black  paper,  scissors,  pliers,  pens,  ink,  paper,  post- 
stamps,  envelopes,  pocket-knife,  black  lead-pencils,  gutta- 
percha dishes,  pails,  towels,  pitcher,  ice-cooler,  soft  water, 
focussing-cloths,  brooms,  hand-brush,  diamond,  cutting- 
board  for  glass,  shelves  for  negatives,  drawers  for  mounts, 
papers,  etc.,  beaker-glasses,  wash-tubs,  scales,  weights  and 
graduated  measures,  dropping-tubes,  test-tubes  and  rack, 
evaporating-dishes,  crucibles  and  furnace,  tongs,  coal  or 
wood,  door-mats,  hat-stand,  artificial  paraphernalia,  as  stuffed 
birds,  beasts,  etc.,  skeletons,  vases,  printing-boxes,  fuming- 
boxes,  forms  for  cutting  out  stereographs,  card-pictures,  etc., 
card-board,  mounts  of  various  sizes,  spatula,  pestle  and  mor- 
tar, India-rubber,  lamps,  candles,  frames  for  photographs, 
solar  camera  and  its  appendages,  solar  microscope  and  acces- 
sories, glue-pot,  tea-kettle,  changing-box  for  dry  plates. 

15.  For  out-door  work  will  be  required  extra :  a  small 
hand-cart  and  tent,  or  dry  collodion  or  tannin-plates,  wax- 
paper,  graduated  tape,  saw,  hatchet,  hammer  and  nails, 
negative-holder. 


CHAPTER  III. 

SPECIALTIES  m  REFERENCE  TO  THE  ARTICLES  IN  THE  PRE- 
CEDING CHAPTER  THE  GLASS-HOUSE,  ETC. 

The  first  thing  which  claims  the  attention  of  the  photo- 
grapher, is  to  secure  to  himself  suitable  rooms.  In  many 
instances  the  artist  has  the  privilege  of  superintending  the 
construction  of  his  glass-house  or  operating-rooms  ;  in  this 
case  he  must  not  only  know  what  is  required  in  such  a  con- 
struction, but  he  must  know  what  arrangements  are  the 
most  appropriate.  The  success  of  many  an  artist  depends 
upon  the  fortuitous  advantages  of  his  glass-house ;  but  these 
fortuitous  advantages  depend  upon  fixed  laws  and  principles 
which  the  photographer  must  learn,  if  he  is  still  ignorant 
of  them.  To  be  brief,  contrast  between  light  and  shade  is 
agreeable  to  the  eye,  whether  tutored  or  untutored ;  where- 
as uniformity  of  light  or  of  shade  is  very  displeasing.  It  is 
not  known  why  this  is  so  any  more  than  why  harmonious 
combinations  of  notes  are  delightful  to  the  ear,  or  why  non- 
coincident  vibrations  produce  discord.  By  means  of  a  hap- 
pily arranged  contrast  of  light  and  shade,  a  stereographic 
roundness  is  communicated  to  pictures  which,  where  this 
contrast  is  deficient  or  quite  wanting,  are  flat  and  in  no  way 
satisfactory ;  and  where  the  contrast  is  exaggerated — where 
the  lights  are  very  bright  and  the  shades  very  deep — where 
the  transition  from  one  to  the  other  is  direct,  and  the  line 
of  demarcation  between  them  is  almost  visible  —  the  round- 
ness becomes  a  complete  distortion  of  solidity.  This  distor- 
tion, arising  from  a  vulgar  contrast,  is  sometimes  so  great 
as  to  cause  the  sitter  to  disclaim  his  own  picture.  The 
qualifications  of  an  artist  are  very  distinct  from  those  of  a 
mere  operator  ;  the  former,  by  reason  of  his  qualifications, 
can  associate  with  gentlemen  and  the  intelligent ;  the  latter 
can  aspire  to  no  higher  companionship  than  with  the  igno- 
rant and  vulgar.  But  the  qualifications  in  question  are  at- 
tributable, in  a  great  measure,  to  a  thorough  knowledge  of 


28  SPECIALTIES — THE  GLASS-HOUSE,  ETC. 

light  iii  reference  to  his  art,  whereby  nature  becomes  na- 
tural. 

If  an  object  be  placed  so  that  the  light  in  one  direction, 
whether  brilliant  or  dull,  falls  perpendicularly  upon  its  sur- 
face, the  picture  will  be  flat  and  disagreeable,  because  there 
is  no  contrast ;  if  the  light  fells  obliquely,  the  contrast  will 
be  displeasing  according  to  its  intensity,  because  the  shadows 
Avill  be  elongated  and  distinctly  marked  from  the  lights.  A 
single  light,  therefore,  can  scarcely  be  said  to  produce  an 
artistic  satisfaction. 

Two  equally  bright  lights,  in  opposite  directions,  or  rather 
in  directions  at  right  angles  to  each  other,  are  very  objection- 
able, because  either  produces  a  bright  circle  of  light  in  the 
eyes,  which  is  repugnant  to  an  artist's  feelings,  from  the  fact 
that  the  picture  is  severely  flat  for  want  of  contrast. 

If  lights  proceed  from  two  directions,  at  right  angles  to 
each  other,  or  somewhere  in  the  neighborhood  of  this  angle, 
of  which  one  is  more  brilliant  than  the  other,  then  it  is  pos- 
sible so  to  arrange  the  sitter  or  model  as  to  satisfy  a  culti- 
vated taste. 

The  greater  the  brilliancy  of  the  light,  the  more  unman- 
ageable it  becomes  in  the  production  of  that  soft  merging  of 
light  into  shade  which  in  photography  is  so  much  required. 
It  is,  therefore,  quite  objectionable  to  use  the  direct  rays  of 
the  sun  in  taking  portraits.  But  during  the  day  these  rays 
proceed  from  three  directions  of  the  compass — in  the  morn- 
ing from  the  east,  at  noon  from  the  south,  and  in  the  evening 
from  the  west ;  from  the  north  alone,  in  the  northern  hemi- 
sphere, the  rays  never  emerge.  But  the  northern  sky  or 
space  is  illumined  by  the  direct  light  from  the  sun,  which, 
by  reflection  and  diffusion,  has  parted  with  much  of  its  of- 
fensive brilliancy,  and  is  rendered  soft  and  manageable. 
The  direct  light  into  the  glass-house,  therefore,  must  enter 
from  the  north  ;  this  is  the  light  which  performs,  or  is  to  per- 
form, the  principal  part  in  the  production  of  a  negative. 
Now  this  single  light,  which  enters  from  the  northern  part 
of  the  hemisphere,  or  a  portion  of  it  at  least,  may  be  soft- 
ened down  by  reflection  from  side-screens,  and  so  directed 
by  them  upon  the  sitter  as  to  make  any  degree  of  agreeable 
contrast.  With  these  principles  in  view,  the  glass-house 
must  be  constructed.  If  the  operating-room  is  situated  in 
the  highest  story  of  a  house,  this  house  ought  to  be  at  least 
as  high  as  the  adjoining  or  contiguous  buildings ;  and  the 
glass  window  on  the  roof  must  be  quite  unobstructed  by 
chimneys  or  trees  in  a  direction  perpendicular  to  its  surface. 


SPECIALTIES  THE  GLASS-HOUSE,  ETC. 


"29 


Supposing  the  ends  of  the  building  in  which  it  is  required  to 
construct  a  photographic  establishment  face  east  and  west, 
the  following  arrangement  is  one  which  I  would  recommend  : 
Let  the  southern  side-wall  be  raised  until  it  is  as  high  as  the 
ridge  of  the  roof ;  in  like  manner  fill  up  to  the  same  height 
the  triangular  space  in  the  end-wall  between  the  chimney 
and  the  southern  wall  now  raised,  either  on  the  eastern  or 
western  end,  as  it  may  happen  to  be  ;  at  a  distance  of  fif- 
teen feet  from  the  end-wall  raise  another,  equally  high,  and 
parallel  with  it,  from  the  southern  side  to  the  ridge  of  the 
roof.  Next  construct  a  water-tight  flat  roof,  beginning  at 
the  side  and  junning  toward  the  north  about  ten  feet.  Where 
this  terminates,  introduce  the  wooden  frame,  the  southern 
portion  inclining  to  the  horizon  toward  the  north  at  an  angle 
of  forty-five  degrees,  to  contain  the  sky-light,  which  may  be 
fifteen  feet  wide  by  twelve  feet  deep,  and  inclined  at  an  angle 
of  forty-five  degrees  with  the  horizon  and  facing  the  north ; 
the  southern  part  of  the  frame  and  the  window,  therefore, 
comprehend  a  right  angle.  Where  it  is  practicable,  it  is 
well  to  have  a  window  in  either  of  the  end-walls,  furnished 
with  sets  of  tight  shutters  about  four  feet  wide,  and  pro- 
ceeding (in  direct  contact,  at  the  commencement,  with  the 
part  of  the  sky-light  nearest  the  north)  downward  to  within 
two  feet  from  the  floor.  Such  side-lights  can  frequently  be 
used  instead  of  screens  ;  and  by  the  adjustment  of  the  shut 
ters,  light  can  be  admitted  as  required,  either  as  regards 
quantity  or  direction,  that  is,  from  the  west  in  the  morning, 
and  from  the  east  in  the  evening.  From  the  lowest  part  of 
the  skylight  downward,  and  right  across  the  room,  the  space 
is  boarded  up  about  four  feet  deep,  and  then  the  remaining 
part  overhead  is  a  flat  ceiling  as  far  as  the  northern  side  of 
the  building.  The  length  of  this  room  must  be  about  thirty 
feet.  The  dark-chamber  and  the  ordinary  work-room  may 
be  constructed  on  the  northern  side,  the  window  of  one 
being  glazed  with  an  orange-yellow  colored  glass,  in  order 
to  absorb  the  actinic  rays,  and  the  other  with  common  crown- 
glass.  On  the  outside  of  the  side-windows,  small  platforms 
are  formed  for  the  reception  of  the  printing-frames,  where 
no  other  room  can  be  had  separately  and  especially  for  the 
direct-printing  department.  The  sky-light  and  the  side- 
lights have  to  be  furnished  with  curtains,  in  order  to  soften 
or  modify  the  light,  which  has  access  according  to  the  cir- 
cumstances of  the  case  or  the  taste  of  the  artist.  The  back- 
grounds are  placed  in  the  space  beneath  the  flat  roof,  on  the 
southern  side,  and  so  far  back  as  to  cut  oif,  as  much  as  pos- 


30 


SPECIALTIES — THE  GLASS-HOUSE,  ETC. 


sible,  the  direct  rays  upon  the  head  of  the  sitter.  The 
northern  end  must  be  papered  with  a  grayish-colored  paper 
— the  more  uniform  the  better — so  as  to  keep  this  part  as 
feebly  lighted  as  possible.  It  is  even  advisable  to  have  the 
part  where  the  camera  is  situated  entirely  curtained  off  from 
the  remaining  space  ;  by  such  an  arrangement,  the  operator 
requires  no  focussing-cloth,  and  the  curtains  being  of  some 
material  such  as  wool,  and  of  a  deadened  color,  the  sitter's 
eyes  are  never  strained  by  looking  in  this  direction. 

It  happens,  however,  very  frequently,  that  photographers 
can  not  direct  the  construction  of  their  rooms,  and  that  the 
sky-light  is  inserted  directly  into  the  slanting  side  of  the 
roof.  In  this  case,  if  the  light  comes  from  the  north,  the 
room  will  have  a  direction  from  east  to  west,  the  sitter  being 
placed  at  either  end,  according  to  circumstances.  Here  only 
one  side-light  can  be  used ;  to  compensate  the  want  of  a 
southern  side-light,  a  screen,  movable  on  an  axis,  is  placed 
in  its  stead,  which,  receiving  light  either  from  above  or  the 
opposite  side,  can  be  made  to  reflect  the  same  in  the  direc- 
tion required. 

Where  the  ridge  of  the  roof  of  a  building  is  directly 
north  and  south,  and  a  sky-light  has  to  be  constructed  on  the 
slanting  roof,  there  seems  to  be  no  alternative  but  to  make 
two  sky-lights,  one  on  either  side,  furnished  with  thick  cur- 
tains within,  and  on  the  put  side  with  a  tall  partition  be- 
tween them,  as  also  one  on  the  southern  side,  to  exclude  the 
direct  rays  of  the  sun ;  or  to  construct  a  suite  of  rooms,  by 
raising  one  of  the  side-walls  of  the  building  as  nearly  in  ac- 
cordance with  the  plan  first  proposed,  with  those  exceptions 
only  which  the  nature  of  the  building  would  demand.  For 
instance,  if  the  building  were  somewhat  wide,  there  would 
be  only  one  side-window,  and  the  facilities  for  printing  would 
not  be  so  great,  unless  some  room  could  be  fixed  up  with  a 
southern  aspect.  The  illumination  of  the  background  by 
the  light  from  the  sky-light,  just  described,  is  uniform,  be- 
cause the  construction  of  the  frame  admits  an  equal  quantity 
at  the  top  as  well  as  at  the  bottom.  The  ordinary  mode  of 
erecting  the  southern  part  of  the  frame,  which  supports  the 
sky-light  in  a  position  perpendicular  to  the  horizon,  excludes 
much  of  the  light,  and  forms  a  shadow  on  the  upper  part  of 
the  background,  unless  a  contrivance  of  reflection  over- 
head causes  the  illumination  to  be  equally  and  uniformly 
distributed. 

The  screens  or  backgrounds  for  placing  behind  the  model 


SPECIALTIES  THE  GLASS-HOUSE,  ETC. 


31 


are  various.  If  the  background  is  to  be  quite  white,  the 
screen  must  be  white  ;  if  intermediate  between  black  and 
white,  the  screen  may  be  gray,  grayish-blue,  blue,  and  vio- 
let. A  red,  orange-red,  yellow,  and  black  screen  will  pro- 
duce a  dark-colored  background,  from  the  fact  that  light, 
impinging  upon  such  surfaces,  reflects  scarcely  any  but  three 
colors,  and  absorbs  almost  all  the  rest ;  but  these  colors  are 
known  by  experience  to  be  possessed  of  little  or  no  actinic 
influence.  Screens,  with  graduated  tints,  shading  off  from 
one  color  into  another,  or  gradually  shading  off  from  a  deep 
to  a  light  color,  are  to  be  highly  recommended  to  an  artistic 
operator.  Other  screens  again  represent  landscapes,  castles, 
shipping,  city  scenery,  etc.,  in  dark-colored  outlines  and 
shading,  on  a  gray  or  bluish-gray  foundation.  Such  repre- 
sentations are  very  pleasing  to  the  uneducated  taste  ;  the 
true  artist  sometimes  seems  to  regard  them  as  finical.  If 
such  backgrounds  are  in  true  perspective,  are  correct  repre- 
sentations of  natural  objects  and  scenery,  and  can  be  well 
focussed  on  the  ground-glass,  I  would  not  hesitate  to  pro- 
nounce them  legitimately  artistic,  and  as  such  they  must  en- 
hance the  value  of  a  card-picture  or  other  photograph.  On 
the  contrary,  if  the  productions  are  rude,  faulty,  and  care- 
lessly shaded,  their  images  on  the  collodion-film  will  be 
equally  so,  and  even  more  so,  by  distortion  from  the  lenses, 
and  will  tend  to  communicate  to  the  photograph  a  vulgar 
appearance. 

On  the  subject  of  light,  a  few  words  more  will  suffice  in 
this  section.  Place  the  model  in  a  very  easy  and  graceful 
manner,  either  standing  or  sitting,  leaning  on  a  pillar,  balus- 
trade, or  small  stand,  in  such  a  manner  that  every  part  is 
nearly  equally  in  focus,  but  especially  the  hands,  face,  and 
feet,  (if  the  latter  are  to  be  visible.)  Avoid  as  much  as  pos- 
sible that  silly  clinging  to  uniformity  in  the  position  of  the 
sitter,  which  some  operators  fall  into,  as  of  laying  the  hands 
folded  together  on  the  lap,  or  of  fixing  the  thumb  in  the  arm- 
hole  of  the  vest.  Such  sameness  becomes  a  characteristic 
of  the  gallery,  and  renders  the  specimens  that  proceed  from 
it  ridiculous.  Old  and  young,  handsome  and  ugly,  the 
grieved  and  the  joyous,  have  all  been  invested  in  the  same 
exuviae,  have  all  been  grouped  or  posed  amid  the  same  ac- 
coutrements. Above  all  things,  endeavor  at  4east  to  pro- 
duce a  variety  of  position  and  paraphernalia  in  the  respect- 
ive members  of  one  and  the  same  family ;  otherwise,  your 
photographs  will  be  no  better  than  the  painting  of  Dr. 


32 


SPECIxVLTIES — THE  GLASS-HOUSE,  ETC. 


Goldsmith's  family  in  the  Vicar  of  Walcefield,  in  which  is 
beheld  an  orange  in  the  hand  of  each  figure.  As  soon  as 
the  figure  or  group  is  fixed  in  a  pleasing,  an  easy,  and  artistic 
position,  the  next  and  a  very  important  business  presents  it- 
self, which  consists  in  illuminating  this  figure  or  group  in 
such  a  way  as  to  obtain  a  clear  and  distinct  image  on  the 
ground-glass  of  the  camera.  If  the  light  falls  too  much  on 
the  head,  prevent  this  by  means  of  the  curtain  on  the  sky- 
light ;  if  the  shadows  are  too  strong,  and  apparent  beneath 
the  eyebrows,  nose,  or  chin,  correct  this  defect  by  means  of 
the  side-light  or  the  movable  screen,  recollecting  the  first 
law  of  reflection  of  light,  which  teaches  that  the  angle  of 
incidence  is  equal  to  the  angle  of  reflection,  so  that,  if  the 
screen  be  inclined  to  the  horizon  at  an  angle  of  forty-five 
degrees,  rays  that  fall  upon  it  through  the  sky-light  wTill  pass 
off  from  it  in  a  direction  parallel  with  the  horizon,  and  in  a 
good  condition  for  destroying  those  horrid  black  specks  of 
shadow  wherever  there  exist  prominences  or  cavities.  The 
great  art  in  photography  is  to  simplify  the  light  to  the  very 
utmost,  to  use  if  possible  light  from  two  directions  alone, 
and  only  that  sort  of  light  which  is  endowed  with  actinic 
influence  on  the  sensitized  plates.  It  will  frequently  hap- 
pen that,  with  the  most  brilliant  illumination,  no  other  but 
a  hazy  image  of  the  model  can  be  obtained  on  the  ground- 
glass  ;  and  where  this  image  is  thus  indistinct  and  fuzzy  on 
the  ground-glass,  it  is  utterly  inrpossible  to  obtain  any  better 
result  on  the  film  of  collodion.  The  haziness  in  question  is 
caused  by  a  multiplicity  of  reflections  of  light,  by  which 
rays  interfere,  cross  each  other,  and  are  jumbled  together  in 
a  very  irregular  and  heterogeneous  manner,  and  also  by  the 
impure  and  unequally  dense  layers  of  air  and  vapor  set  in 
motion  in  the  room,  which  produce  an  atmosphere  in  front 
of  and  around  the  sitter  similar  to  those  dazzling  ascending 
columns  of  air  visible  at  the  sides  and  on  the  top  of  a  stove. 
To  avoid  the  first  cause,  it  is  recommended  to  glaze  the  sky- 
light with  glass  containing  cobalt,  which  communicates  to  it 
a  blue  or  violet  tinge.  Such  glass  excludes  all  superfluous 
light,  allows  only  actinic  rays  to  penetrate,  and  subdues  the 
illumination  to  such  a  degree  as  to  render  the  image  on  the 
ground-glass  quite  distinct  and  agreeable  to  the  eye.  Al- 
though the  room,  by  such  glazing,  is  considerably  darkened, 
the  operations  in  photography  are  incomparably  superior  in 
result,  and  the  time  of  exposure  is  not  lengthened.  The 
second  cause  is  obviated  by  preserving  a  uniform  tempera- 


SPECIALTIES — THE  GLASS-HOUSE,  ETC. 


S3 


ture  in  the  room,  and  by  having  the  currents  of  ventilation 
proceeding  to  their  exit  at  some  distance  from  the  sitter. 
Let  me  finally  impress  upon  every  photographer  the  abso- 
lute necessity  he  is  placed  in  of  learning  to  manage  the 
light,  before  he  can  ever  hope  to  be  successful  in  the  subse- 
quent operations  with  chemical  materials.  An  imperfectly 
lighted  picture  can  never  be  metamorphosed  afterward  into 
a  respectable  production. 


CHAPTER  IV. 


SPECIALTIES  CONTINUED.  THE  CAMERA  AND  LENS. 

The  second  most  essential  thing  after  a  good  light,  and  a 
successful  illumination  of  the  object,  is  a  compound  lens,  so 
far  corrected  for  spherical  and  chromatic  aberration  as  to 
reproduce  on  the  ground-glass  an  image  in  which  straight 
lines  are  exhibited  straight,  and  all  the  parts,  both  in  the 
central  and  peripheral  portions,  are  clearly  defined  and  free 
from  spectral  colors.  ISTo  single  lens  can  be  practically 
ground  and  polished  so  as  to  be  free  from  spherical  aberra- 
tion ;  which  means  that  no  lens  can  be  constructed  so  that, 
with  the  whole  opening,  the  rays  both  through  the  center 
and  all  the  way  to  the  edges  shall  be  refracted  to  one  point. 
The  focus  of  those  rays  which  are  transmitted  through  the 
lens  near  the  periphery,  is  nearer  to  the  lens  than  of  those 
which  pass  through  the  center.  Hence  exist  a  multiplicity 
of  foci,  thus  converting  that  which  ought  to  be  a  point  into 
a  circular  space  ;  and  that  which  ought  to  be  a  line,  into  a 
rectangular  or  curvilinear  space ;  hence  the  origin  of  indis- 
tinctness and  haziness  in  the  photograph — the  picture  is  de- 
void of  sharpness  and  fine  definition.  If  the  optician  were 
able  to  grind  lenses  with  ellipsoidal  surfaces,  then  a  single 
lens  might  be  constructed  so  as  to  be  totally  free  from  this 
sort  of  error  or  aberration.  This,  however,  is  manifestly  a 
practical  impossibility.  The  form  of  lens  which  distorts 
the  least,  that  is,  which  has  the  least  spherical  aberration, 
is  the  one  which  is  well  known  as  the  crossed  lens,  whose 
radii  of  curvature  are  in  the  proportion  of  one  to  six. 
Spherical  aberration  may  be  corrected  partly  by  a  combina- 
tion of  lenses  and  partly  by  the  use  of  diaphragms,  the  lat- 
ter of  which  exclude  all  but  the  central  rays,  or  all  but  the 
peripheral  rays. 

Chromatic  aberration  arises  from  the  difference  in  the  re- 
frangibilities  of  the  colored  rays  in  the  spectrum,  and  the 
decomposition  of  white  light  into  the  colored  or  spectral 
light,  whenever  it  is  transmitted  through  a  homogeneous 


SPECIALTIES  THE  CAMERA  AND  LENS. 


35 


transjmrent  medium  whose  two  surfaces  are  not  parallel. 
But  the  two  surfaces  of  a  lens  are  never  parallel ;  therefore 
every  simple  and  homogeneous  lens  must  decompose  light 
into  the  spectral  colors  of  which  the  violet  on  one  side  is 
much  more  refrangible  than  the  red  on  the  other.  On  this 
account  the  focus  of  the  red  light  will  be  more  remote  from 
the  lens  than  that  of  the  violet  light.  This  sort  of  aberra- 
tion, therefore,  has  the  same  tendency  as  spherical  aberra- 
tion to  convert  points  and  lines  into  circular,  rectangular, 
or  curvilinear  spaces,  with  an  additional  inconvenience  aris- 
ing from  the  different  colors,  which  it  is  well  known  are 
possessed  of  very  different  degrees  of  actinism.  Now, 
when  both  these  causes  of  distortion  and  indistinctness  ex- 
ist in  a  lens  or  in  a  combination  of  lenses,  it  is  not  in  the 
power  or  skill  of  the  photographer  to  obtain  a  well-defined, 
sharp,  and  actinically  well-developed  picture.  Some  sorts 
of  glass  refract  light  more  than  others  ;  again,  some  decom- 
pose light  into  the  spectral  colors  differently,  so  that  the 
angle  between  the  extreme  rays,  the  red  and  the  violet, 
where  the  refracting  angle  of  the  prism  or  lens  is  the  same, 
but  the  material  different,  is  not  a  fixed  quantity.  Com- 
bining these  angular  differences,  the  differences  in  the  re- 
fracting powers  of  transparent  media  and  the  varying  radii 
of  curvature,  mathematicians  are  now  able  to  devise  a  variety 
of  combinations  of  lenses  which  are  practically  free  from  the 
aberrations  in  question.  Generally  crown-glass  and  flint- 
glass  are  combined  in  accordance  with  the  principles  just 
alluded  to.  Such  a  combination  corrects  partially ;  it  is  a 
decided  improvement  over  any  single  lens  as  regards  fine 
definition  ;  but  what  it  gains  in  definition  it  loses  in  magni- 
fying power.  A  triplet,  or  a  combination  of  three  lenses, 
properly  constructed,  is  an  improvement  upon  the  doublet ; 
and  a  pair  of  doublets  whose  radii  and  distances  are  mathe- 
matically and  optically  calculated,  can  be  made  to  produce 
more  correction  than  it  is  possible  to  obtain  from  a  triplet. 
Three  pairs,  too,  will  effect  more  than  two ;  but,  unfortun- 
ately, whatever  is  now  gained  in  focal  sharpness  is  diminished 
in  value  by  the  absorbing  power  of  the  different  lenses  ;  so 
that  when  the  combinations  increase  in  number,  the  light 
which  finally  emerges,  however  much  corrected,  becomes 
more  and  more  actinically  weak.  For  photographical  pur- 
poses, a  pair  of  compound  lenses  can  be  constructed  and 
adjusted  so  as  to  be  practically  perfect.  We  are  indebted 
to  Dolland  for  the  first  achromatic  combination.  Doublets 
and  triplets  are  decidedly  the  best  arrangements  for  land- 


3G 


SPECIALTIES  THE  CAMERA  AND  LENS. 


scape  photography  ;  whereas  two  pairs  of  doublets,  adjusted 
at  a  given  distance  apart,  or  at  a  variable  distance  apart, 
are  preferred  for  portraiture.  The  nearer  the  pairs  of  com- 
binations approach  each  other,  the  greater  the  magnifying 
power  ;  the  maximum  power  existing  when  they  are  in  jux- 
taposition. When  a  tube  is  fitted  up  so  that  one  of  the 
combinations  admits  of  motion  by  a  rack  and  pinion,  its  focal 
length  can  be  thus  changed,  and  is  practically  good  within 
certain  limits.  With  such  tubes,  too,  it  becomes  an  easy 
matter  to  adjust  a  pair  of  them  for  stereoscopic  purposes. 

The  following  rules  and  information  will  be  found  useful 
for  ascertaining  the  conrparative  value  of  the  different  tubes 
in  the  market. 

To  find  the  Principal  Focus  of  a  Lens. — Fix  the  lens  in  a 
tube  or  aperture  in  the  camera;  then  turning  the  camera 
to  the  moon,  adjust  the  slide  until  the  image  on  the  ground- 
glass  is  perfectly  in  focus  ;  measure  the  distance  from  the 
ground-glass  to  the  nearest  surface ;  then  with  a  pair  of  cal- 
lipers take  the  thickness  of  the  lens  and  divide  this  thickness 
by  two ;  now  add  this  half  to  the  first  distance,  which  will 
be  the  focal  distance  exactly  if  the  lens  is  double-convex  and 
its  radii  of  curvature  are  equal.  Proceed  in  like  manner 
with  a  compound  lens  ;  the  result  will  be  very  nearly  cor- 
rect. Where  the  tube  contains  two  pairs  of  combinations, 
a  similar  method  may  be  adopted  without  much  error.  In 
speaking  of  the  focal  distance  of  a  lens,  or  of  a  combination, 
it  is  customary  simply  to  measure  the  space  between  the 
ground-glass  and  the  nearest  surface  of  the  last  combina- 
tion, after  focussing  the  moon  or  the  sun. 

To  find  the  Equi-distant  Conjugate  Foci  of  a  Lens  or 
Combination. — Adjust  the  object,  as,  for  instance,  a  card- 
picture,  in  front  of  the  lens  or  combination  in  the  camera, 
until  the  image  on  the  ground-glass  is  of  an  exactly  equal 
size  with  the  object  when  in  perfect  focus.  Measure  the 
distance  from  the  image  to  the  object  and  divide  this  dis- 
tance by  two  ;  the  quotient  will  be  the  quantity  required. 

To  find  the  Comparative  Value  of  Two  Lenses  or  Com- 
binations which  produce  the  same  Sized  Image  of  an  Object 
at  the  same  Distance. — Take  the  difference  between  the  equi- 
distant conjugate  focus  and  the  principal  focus  of  either  lens ; 
the  smaller  this  difference  the  better  the  lens,  because  the 
focal  depth  or  penetration  is  greater ;  that  is,  objects  farther 
apart  can  be  brought  into  focus  consentaneously  and  with 
more  facility  when  this  difference  is  small  than  when  it  is 
large.    If  this  difference  were  zero,  a  lens  would  be  perfect. 


SPECIALTIES  THE  CAMERA  AND  LENS. 


37 


To  find  the  Magnifying  Power  of  a  Lens  or  Combination. 
— On  a  sheet  of  card-board,  in  the  middle,  construct  a  circle 
one  inch  in  diameter,  for  instance  ;  place  this  sheet  on  a 
table.  Insert  the  lens  or  tube  into  a  piece  of  wood  placed 
horizontally  over  the  circle,  and  raise  or  depress  it  by  blocks 
or  books  until  the  circle  is  seen  most  distinctly  when  viewed 
with  one  eye.  Now,  by  a  little  practice,  with  both  eyes 
open,  one  looking  through  the  tube  and  the  other  on  the 
side  upon  the  paper,  marks  can  be  made  on  the  board  at 
the  extremities  of  a  diameter  of  the  magnified  circle  ;  be- 
cause the  eye  which  is  free  can,  by  sympathy,  see  the  mag- 
nified image  which  the  other  eye  beholds,  and  the  pencil  at 
the  same  time.  After  this,  measure  the  distance  between 
the  pencil-marks,  and  divide  this  distance  by  the  diameter 
of  the  real  circle  ;  the  quotient  will  indicate  the  number  of 
times  the  image  is  larger  than  the  object,  which  number  is 
the  magnifying  power. 

To  find  the  Comparative  Magnif  ying  Power  of  Lenses  or 
Combinations. — Measure  the  distance  in  either  between  the 
lens  and  the  ground-glass  when  the  moon  is  in  focus,  or 
measure  the  size  of  the  image  ;  the  greater  this  distance  or 
image,  the  less  the  magnifying  power.  The  quotient  aris- 
ing by  dividing  one  distance  with  the  other  will  give  the 
amount  of  magnifying  power  in  favor  of  the  lens,  whose  dis- 
tance is  the  shorter. 

To  find  a  Single  Lens  equivalent  in  Power  to  a  Compound 
Lens. — If  a  compound  lens  and  a  single  lens  be  placed  so 
that  their  centers  are  at  the  same  distance  from  the  moon  or 
a  distant  object,  for  instance ;  then,  if  they  produce  the  same 
sized  picture,  one  will  be  equivalent  to  the  other.  (For 
further  information  vide  chapters  on  Microphotography  and 
Macrophotography.) 

To  ascertain  whether  a  Combination  is  corrected  for 
Spherical  Aberration. — Draw  two  parallel  straight  lines,  ex- 
actly an  inch  apart,  and  two  or  three  inches  long,  on  a  piece 
of  card-board.  Move  the  slide  until  they  are  correctly  in 
focus  on  the  ground-glass,  and  until  the  width  between  the 
lines  is  two  inches.  If  this  distance  remains  the- same,  that 
is,  if  the  lines  do  not  deviate  from  straight  lines  and  from 
parallelism,  the  combination  is  aplanatically  correct ;  if,  on 
the  contrary,  the  images  of  the  straight  lines  are  curves,  the 
spherical  aberration  has  not  been  corrected.  Apply  a  dia- 
phragm of  small  opening  in  front  of  the  combination  ;  it  will 
be  perceived  that  the  curvature  of  the  lines  will  diminish 
as  the  aperture  diminishes.    If  with  a  very  small  aperture 


38 


SPECIALTIES — THE  CAMERA  AND  LENS. 


the  lines  are  still  curved,  the  combination  is  worthless ; 
whereas,  if  the  lens  or  combination  can  be  used  without  a 
diaphragm  and  still  produces  straight  and  parallel  lines  in 
the  images,  such  a  magnifier  will  be  very  valuable. 

To  ascertain  whether  a  Lens  or  Combination  is  corrected 
for  Chromatic  Aberration. — Adjust  the  slide  most  accur- 
ately, so  that  the  image  of  an  object  is  very  clear  and  dis- 
tinct. Next  see  that  the  surface  of  the  collodionized  plate  is 
exactly  coincident  with  the  ground-surface  of  the  glass,  that 
is  to  say,  at  the  same  distance  from  the  nearest  surface  of 
the  lens.  Sensitize  the  collodion  film  and  take  a  picture. 
If,  when  developed  and  fixed,  this  picture  is  as  sharp  and 
well-defined  as  it  was  on  the  ground-glass,  the  lens  is  achro- 
matic ;  if,  on  the  contrary,  the  contrast  between  light  and 
shade  is  imperfect,  and  the  definition  and  sharpness  feeble, 
the  combination  has  been  either  over-corrected,  under-cor- 
rected, or  not  corrected  at  all.  The  actinic  rays  are  on  the  vio- 
let side  whose  refrangibilities  are  greater  than  those  of  the  red 
rays  ;  their  focal  distance,  therefore,  is  shorter.  Focus  again, 
and  after  this  has  been  accomplished  draw  the  slide  contain- 
ing the  ground-glass  outward  about  one  sixteenth  part  of  an 
inch,  insert  the  sensitized  plate,  expose,  develop,  and  fix,  as 
before.  If  the  picture  is  better  than  before,  it  shows  that 
the  actinic  focus  is  longer  than  the  luminous,  and  that  the 
combination  has  been  over-corrected.  By  proceeding  in  this 
way,  it  can  be  ascertained  exactly  how  much  the  slide  has  to 
be  drawn  out  in  order  to  produce  a  picture  as  sharp  as  that 
on  the  ground-glass.  After  this  distance  is  found,  the  ground- 
glass  has  to  be  advanced  or  sunk  deeper  in  its  frame  by  this 
amount,  whereby  the  camera  becomes  adjusted  to  the  tube. 
Should  it  happen  that  the  slide  has  to  be  pushed  in  after 
focussing  in  order  to  obtain  sharp  definition  on  the  collodion, 
it  is  an  indication  that  the  lens  is  under-corrected  or  not  cor- 
rected at  all.  Where  a  lens  requires  no  adjustment  of  the 
ground-glass,  it  is  said  to  be  achromatically  correct,  or  that 
the  actinic  and  luminous  foci  are  coincident.  The  value  of 
a  lens  in  this  respect  is  inversely  proportionate  to  the  amount 
of  adjustment  required ;  that  is,  the  greater  the  amount  of 
adjustment,  the  less  its  value. 

Other  methods  have  been  proposed  to  test  the  coincidence 
of  the  actinic  and  luminous  foci.  One  consists  in  pasting  a 
newspaper  on  a  flat  board,  and  erecting  the  latter  perpen- 
dicular to  the  horizon  and  in  front  of  the  opening  of  the  lens, 
so  that  the  axis  of  the  lens  passes  through  the  center  of  the 
newspaper  and  at  right  angles  to  it.    The  operator  next  ob- 


SPECIALTIES  THE  CAMERA  AND  LENS. 


30 


tains  a  sharp  focus  upon  the  central  parts,  and  afterward  ob- 
tains a  positive  of  the  object.  If  the  central  parts  are  still 
in  focus  in  the  picture,  the  combination  has  been  achromat- 
ically  corrected ;  if  the  parts  intermediate,  from  the  center  to 
the  periphery  arc  in  focus,  the  lens  has  been  over-corrected  ; 
and  more  so  if  the  marginal  portions  alone  are  in  focus  ; 
whereas,  if  the  picture  is  nowhere  sharp,  it  is  probable  the 
lens  has  not  been  sufficiently  or  not  at  all  corrected  for  chro- 
matic aberration. 

A  second  method  is  to  focus  first  in  the  ordinary  way ; 
then,  placing  a  piece  of  violet-colored  glass  in  front  of  the 
lens,  to  focus  again ;  if  the  two  foci  coincide,  the  actinic  and 
luminous  foci  coincide. 

A  third  method  is  that  proposed  by  Claudet,  which  consists 
in  placing  printed  cards  at  short  distances  apart,  as,  for  in- 
stance, of  one  tenth  of  an  inch,  in  grooves  on  an  inclined 
plane  resting  on  a  table  in  front  of  the  tube.  Let  there  be 
five  cards  so  arranged,  and  focus  upon  the  middle  one.  If 
the  first  or  second  is  in  focus,  the  lens  is  under-corrected ;  if 
the  middle  one  is  sharp,  the  lens  is  unexceptionable  ;  and  if 
the  fourth  or  fifth  is  well  defined,  the  combination  is  over- 
corrected. 

For  an  over-corrected  lens  or  combination  the  ground-glass 
has  to  be  set  back  by  introducing  thin  pieces  of  card-board 
between  it  and  the  ledge  of  the  slide  in  which  it  rests ;  and 
where  the  correction  has  been  defective,  the  glass  has  to  be 
sunk  deeper  as  before  mentioned. 

If  a  combination  has  been  thoroughly  corrected,  I  throw 
aside  the  ordinary  ground-glass  slide  entirely,  and  focus  upon 
a  piece  of  glass  of  the  same  size  as  the  collodionized  plate, 
and  introduced  into  the  self-same  aperture  which  is  to  con- 
tain the  negative.  In  this  way  the  collodion-surface  and  the 
ground-surface  must  necessarily  coincide. 

How  to  buy  a  Good  Lens. — Do  not  purchase  a  second- 
hand tube  of  any  one,  if  you  are  a  beginner  in  the  art  of  pho- 
tography;  but  throw  yourself  implicitly  and  in  full  confidence 
into  the  hands  of  a  photographic  house  of  decided  reputation, 
who  will  furnish  you  with  a  lens  and  camera  in  perfect  ad- 
justment and  in  working  condition.  The  tubes  manufac- 
tured in  this  country  by  two  or  three  different  firms,  are  not 
inferior  to  the  best  from  abroad ;  and  the  advantage  you 
have  in  dealing  directly  with  them  or  their  immediate  agents 
is,  that  if  by  chance  a  lens  turns  out  in  any  way  defective, 
you  can  immediately  obtain  redress  by  an  exchange.  As 
soon  as  an  operator  is  sufficiently  skilled  in  optics  and  their 


40 


SPECIALTIES  THE  CAMERA  AND  LENS. 


application  to  the  heliographic  art,  he  will  be  in  a  condition 
to  rely  upon  his  own  judgment,  and  to  make  his  purchases 
where  pecuniarily  they  are  the  most  advantageous.  The 
best  criterion  by  which  to  ascertain  whether,  after  purchas- 
ing an  adjusted  tube  and  camera,  the  actinic  and  luminous 
foci  coincide,  is  to  take  the  plate-holder  containing  a  plate  of 
glass  with  the  slide  drawn  and  place  it  ivpon  a  table,  collo- 
dion side  uppermost ;  by  the  side  of  this  place  the  ground- 
glass  slide  with  the  ground-surface  uppermost.  Placing  a 
rigid  flat  ruler  over  either  of  these,  it  will  be  easy  to  measure 
the  distance  from  each  glass  surface  to  the  edge  of  the  ruler. 
Where  these  two  distances  coincide,  there  has  been  no  need 
of  adjustment ;  and  the  lens  may  be  regarded  as  good.  If 
the  difference  is  well  marked,  I  would  recommend  you  to 
return  the  tube  and  get  a  better. 

Supposing,  furthermore,  lenses  to  be  aplanatic  and  achro- 
matic, there  exist  special  differences  by  which  their  relative 
values  can  be  distinctly  estimated.  The  value  of  such  in- 
struments depends  upon  the  extent  of  picture  in  perfect  de- 
finition which  can  be  obtained  by  them,  with  a  given  open- 
ing, focal  distance,  and  diaphragm,  and  on  the  velocity  with 
which  this  work  can  be  accomplished.  If  of  two  lenses  of 
equal  opening  and  equal  focal  distance,  the  one  will  produce 
as  sharp  and  large  a  picture  without  a  stop  as  the  other 
can  with  a  diaphragm ;  the  former  is  very  much  superior, 
because,  with  much  more  light,  the  operation  of  actinism 
will  be  relatively  quicker.  In  like  manner,  if  of  two  lenses 
whose  three  parts,  as  enumerated  above,  are  all  equal,  but 
the  picture  of  one  is  considerably  larger  than  that  of  the 
other,  and  in  every  respect  as  well  defined,  the  comparative 
value  is  easy  to  determine.  Wherever  this  difference  in  the 
size  of  the  picture  exists,  other  things  remaining  the  same, 
it  will  be  found  that  the  lens  which  produces  the  larger 
picture  will  likewise  comprehend  a  larger  angular  space  con- 
taining objects.  Drawing  imaginary  lines  from  the  two  ex- 
tremities of  the  landscape,  for  instance,  through  the  center 
of  the  lens  or  combination,  to  the  corresponding  extremities 
of  the  picture,  two  isosceles  triangles  are  formed  with  their 
vertical  angle  at  the  center.  This  angle  or  opening  of  the 
two  outside  rays  constitutes  what  is  denominated  the  angu- 
lar aperture  of  the  lens.  The  greater  this  angle,  the  other 
values  remaining  the  same,  the  greater  the  practical  worth 
of  the  lens.  For  the  purposes  of  portraiture,  the  lenses  in 
general  have  but  a  small  angular  aperture,  and  produce  a 
picture  but  little  more  in  diameter  than  half  the  focal  dis- 


SPECIALTIES  THE  CAMEEA  AND  LENS.  41 


tance.  The  relation  between  the  opening  of  the  lens,  the 
aperture  in  the  diaphragm,  the  focal  distance  and  the  dia- 
meter of  the  picture,  as  given  in  the  Chimie  JPhotographique, 
are  as  follows  :  Calling  the  focal  distance  unity,  then  the 
diameter  of  the  lens  will  be  }  of  this  unity,  that  of  the  stop 
3*5-,  and  that  of  the  picture  |.  If  the  diameter  of  the  dis- 
tinct picture  is  equal  to  the  focal  distance,  the  angular  aper- 
ture will  be  about  53°  ;  and  if  this  angle  be  90°,  the  dia- 
meter of  the  picture  will  be  about  twice  as  great  as  the 
focal  distance.  It  is  asserted  that  the  new  globe-tubes,  the  in- 
vention of  C.  C.  Harrison,  have  an  aperture  of  ninety  degrees, 
and  that  they  are  free  from  spherical  and  chromatic  aberra- 
tion ;  they  will  therefore  be  in  a  condition  to  produce  large 
pictures  with  a  small  focus.  The  only  disadvantages  which 
they  probably  possess  will  be  a  deficiency  of  light,  owing  to 
the  smallness  of  the  aperture  in  the  stops  ;  an  inequality  of 
action  from  the  center  to  the  peripheral  parts  ;  and  the  pro- 
duction of  what  is  denominated  the  "  ghost"  on  the  center 
of  the  picture,  owing  to  reflections  between  the  lenses  of 
the  combination.  For  architectural  and  landscape  photo- 
graphy they  must  be  inestimable,  if  the  assertion  of  their 
merits  is  true. 

The  firms  in  this  country  that  have  gained  a  well-earned 
reputation  for  the  manufacture  of  portrait,  etc.,  lenses  are 
those  of  C.  C.  Harrison  &  Co.,  and  of  Holmes,  Booth,  and 
Haydens  ;  in  Great  Britain,  those  of  Ross,  Dallmeyer,  Grubb, 
etc. ;  in  France,  of  Jamin,  etc. ;  in  Germany,  of  Voightkender, 
etc. 


CHAPTER  V. 


SPECIALTIES  CONTINUED.  THE  CAMERA. 

The  camera  obscura  was  the  invention  of  Porta,*  a  Nea- 
politan ;  this  instrument  is,  in  fact,  a  miniature  glass-house, 
a  conjugate  glass-house,  which  admits  no  light  but  that  which 
passes  through  the  lens.  The  ground-glass  is  the  screen, 
which  must  be  at  right  angles,  and  slide  at  right  angles  with 
the  axis  of  the  lens.  The  model,  therefore,  or  sitter,  must 
likewise  be  so  arranged  that  the  various  component  parts 
that  have  to  appear  in  the  picture  shall  be  as  much  as  pos- 
sible in  a  plane  perpendicular  to  the  optical  axis.  In  this 
case,  it  becomes  the  duty  of  the  photographic  artist,  as  soon 
as  his  model  is  gracefully  and  compactly  arranged,  to  fix 
upon  the  point  which  is  to  be  the  center  of  the  picture,  as, 
for  instance,  the  eye  of  the  sitter,  then  to  reconnoiter  the 
ground,  and  examine  the  inclination  of  the  different  parts  of 
the  figure  forming  the  visible  surface,  and  to  ascertain  the 
direction  of  a  line  drawn  from  the  eye  at  right  angles  to  this 
surface  ;  now  bring  the  camera,  raise  it  and  incline  it  until 
the  axis  of  the  lens  coincides  with  this  previously  deter- 
mined direction.  In  this  position,  it  will  be  possible  to  ob- 
tain a  picture  in  which  the  different  parts  are  almost  equally 
in  focus.  Before  you  begin  to  obtain  the  focus  on  the 
ground-glass,  fix  the  lens  in  its  brass  slide  in  the  middle  of 
its  motion  by  the  rack  and  pinion.  Next  move  the  bellows- 
slide  of  the  camera  until  the  image  on  the  glass  is  distinct, 
and  clamp  the  slide  ;  finally  obtain  a  sharp  focus  by  means 
of  the  thumb-screw  on  the  pinion-wheel.  With  a  quick 
motion  backward  and  forward  of  the  lens,  the  point  of 
sharpest  definition  can  easily  be  descried  with  the  naked  eye, 
as  long  as  the  image  is  much  smaller  than  the  object ;  but 
in  copying  photographs  or  engravings,  where  the  picture  is 
to  be  of  equal  size  with  the  original,  it  is  not  easy  to  obtain 
the  exact  focus ;  in  this  case  the  microscope  is  called  into 

*  Porta,  Giovanni  Battiste  Delia,  was  born  at  Naples,  in  1510. 


SPECIALTIES  C01STINTJED — THE  CAMERA. 


43 


requisition.  The  first  thing  to  be  done,  where  this  difficulty 
exists,  is  to  hunt  about  upon  the  original  photograph  or  en- 
graving for  some  distinct  landmark,  as  a  very  minute  circle, 
or  a  couple  of  lines  in  apparent  juxtaposition,  or  the  open- 
ing in  the  letter  e  or  0,  or  the  extreme  lines  on  the  sides  of 
a  blade  of  grass  ;  the  space  between  these  will  become  very 
manifest  under  the  microscope,  and  by  a  sweep  of  the  lens 
backward  and  forward,  the  boundary-lines  can  be  designated 
when  most  sharp.  It  requires  much  practice  to  focus  well 
in  copying ;  hence  it  is  that  few  photographers  are  good 
copyists.  The  microscope  suitable  for  such  purposes  may 
be  a  common  magnifying-glass,  the  front  lens  of  one  of  the 
stereoscopic  tubes,  or  a  compound  microscope  of  low  power. 
An  error  in  the  focal  distance  of  one  sixteenth  of  an  inch, 
in  portraiture,  is  scarcely  perceptible  ;  whereas  the  same 
amount  of  error  in  copying  will  produce  a  total  failure  in 
the  negative  or  positive.  In  taking  a  view,  and  in  copy- 
ing, it  is  frequently  a  plan  to  be  recommended,  to  focus  a 
point  midway  between  the  center  of  the  picture  and  the  out- 
side. This  is  said  to  equalize  the  definition ;  it  is  essentially 
a  means  of  dividing  the  error  of  spherical  or  chromatic 
aberration,  where  either  exists.  The  eye  of  the  sitter  may 
regard  some  fixed  point  on  a  level  with  its  direction ;  care 
must  be  taken  that  it  is  neither  raised  nor  depressed  nor  in 
any  way  strained.  By  looking  at  some  point  on  the  camera, 
which  is  situated  in  the  darkest  part  of  the  glass-house,  the 
eyes  will  be  able  to  remain  quite  at  ease,  even  whilst  stead- 
fastly gazing  at  this  point ;  if,  however,  the  sight  were 
directed  to  a  point  brilliantly  lighted,  the  eyelids  would  in- 
voluntarily close,  and  the  pupil  contract,  by  which  the  pic- 
ture would  be  impaired. 

The  photography  of  architecture  and  of  landscapes  re- 
quires absolutely  that  the  camera  be  horizontal,  and  so  does 
that  of  card-pictures,  when  the  whole  figure  is  compre- 
hended, in  order  to  avoid  the  pyramidal  inclination  of  parts 
which  in  nature  are  parallel.  This  pyramidal  distortion  is 
the  consequence  of  the  obliquity  of  the  rays  as  they  are 
thus  made  to  enter  the  lens,  and  for  which  obliquity  the 
lens  has  not  been  corrected.  On  account  of  the  large  angle 
which  a  card-picture  must  necessarily  comprehend,  a  long- 
focussed  lens  is  preferred,  much  longer  than  is  required  for 
taking  a  portrait  at  the  same  distance.  It  is  a  frequent  oc- 
currence to  those  who  occupy  themselves  with  out-door  pho- 
tography not  to  be  able  to  comprehend  certain  very  desir- 
able elevations  within  tho  compass  allotted  to  the  photo- 


44 


SPECIALTIES  CONTINUED — THE  CAMERA. 


graph  without  inclining  the  tube  upward ;  but  the  tube 
must  remain  horizontal ;  therefore  the  only  alternative  re- 
maining is  to  raise  the  camera  upon  a  platform  or  to  place  it 
on  a  window-sill,  on  the  roof  of  a  house,  on  the  branch  of  a 
tree,  or  on  the  spokes  of  two  ladders,  tied  or  hinged  at  the 
top,  and  with  the  feet  drawn  out  so  as  to  form  a  large  base 
between  them.  Lenses  with  large  aperture  are  exceedingly 
useful  in  such  cases,  as,  for  instance,  in  taking  views  of 
churches,  public  buildings,  etc.,  from  the  opposite  side  of  the 
street.  The  great  desideratum  has  been  to  find  a  lens  of  short 
focus  and  large  angle  for  such  sort  of  work,  which  can  not  be 
performed  with  lenses  of  long  focus  and  small  aperture. 

If  the  objects  in  the  foreground  of  a  view,  as  is  the  case 
with  a  stereograph,  are  to  be  the  principal  items  of  atten- 
tion, the  lens  will  have  to  be  focussed  either  upon  the  cen- 
tral object  or  upon  one  intermediate  between  the  center  and 
the  edge.  In  this  case,  unless  the  difference  between  the 
focus  of  parallel  rays  and  the  focus  at  an  infinite  distance  be 
exceedingly  small,  almost  all  remote  objects  will  be  slightly 
out  of*  focus,  and  the  picture  in  the  distant  background  will 
be  defective.  To  counteract  this  effect,  a  much  larger  lens 
is  employed,  which  is  carried  to  some  distance  from  the 
principal  objects,  until  the  picture  be  of  the  same  size  as 
was  intended  to  be  taken  with  the  lens  of  shorter  focus.  The 
camera,  too,  in  such  a  case,  must  be  raised  above  the  hori- 
zon, but  focussed  parallel  to  it.  The  scenery  in  close  prox- 
imity can  be  thus  excluded,  and  the  distant  view  will  be 
nearly  equally  well  defined  and  in  true  perspective.  A 
small  view  taken  in  this  manner  can  be  enlarged  afterward 
either  into  a  negative  or  positive,  as  may  be  required,  by  the 
method  which  is  fully  explained  hereafter. 

There  are  certain  rules  to  be  observed  in  field-photography 
in  reference  to  the  light,  as  in  room-photography. 

The  first  is,  not  to  place  the  axis  of  the  camera  in  the 
same  straight  line  with  the  sun  and  the  object.  This  means 
that  a  picture  is  not  to  be  taken  in  the  direction  of  the  sun's 
rays,  where  the  front  and  central  objects  are  equally  illu- 
mined, and  consequently  must  be  very  flat  in  the  photo- 
graph ;  it  would  be  equally  absurd  to  attempt  a  picture  in 
the  shade,  whilst  the  sun  is  shining,  as  it  were,  into  the 
camera  through  the  lens. 

An  inclination  of  the  axis  of  the  camera  with  the  direc- 
tion of  the  sun's  light,  to  the  amount  of  forty-five  degrees, 
will  produce  an  agreeable  contrast  of  light  and  shade.  It 
is  very  possible  and  very  probable  that  such  an  illumina- 


SPECIALTIES  CONTINUED — THE  CAMERA. 


45 


tion  from  the  unobscured  rays  will  produce  too  strong 
a  contrast,  and  thus  give  rise  to  a  very  hard  picture.  The 
best  effects  are  attained  when  the  sun  is  obscured  by  a 
white  cloud ;  the  lights  and  shades  still  exist  with  the  addi- 
tion of  decided  middle  tints,  giving  the  photograph  the  ap- 
pearance of  an  artistic  production. 

With  these  recommendations  in  view,  the  photographer 
must  visit  the  ground  previously  to  his  taking  a  picture,  in 
order  to  ascertain  at  what  time  of  the  day  the  light  falls 
upon  it,  or  can  fall  upon  it,  so  as  to  produce  the  best  photo- 
graphic illumination  ;  this  sort  of  proceeding  distinguishes 
the  artist  from  the  operator,  and  gives  the  same  distinction 
to  his  work.  It  may  happen  that  the  principal  object  in  a 
landscape,  which  it  is  required  to  photograph,  is  so  situated 
as  not  to  receive  the  direct  light  of  the  sun,  as  is  the  case 
with  many  northern  aspects.  The  artist,  in  such  a  case,  will 
have  to  wait  for  a  cloudy  day,  when  the  direct  light  of  the 
sun  can  produce  no  real  shadows,  and  when  perhaps  a  white 
cloud  in  the  north-east  or  north-west  may  be  found  to  make 
sufficient  contrast. 

Cameras  for  lenses  of  short  focus  can  be  roughly  adjusted 
to  focus  by  means  of  the  bellows-slide,  and  afterward  finely 
adjusted  with  the  thumb-screw  on  the  lens ;  but  when  the 
focus  is  long,  the  thumb-screw  is  useless,  unless  attached  to 
a  long  lever,  as  was  formerly  used  in  the  Lucernal  micro- 
scope; in  such  cameras,  the  bellows-slide  has  a  rough  or 
quick  motion,  and  a  slow  or  fine  motion  by  means  of  a 
thumb-screw  in  front  of  the  operator  or  on  the  posterior 
part  of  the  slide.  Such  cameras,  too,  by  reason  of  their 
length,  have  to  be  supported  on  two  camera-stands,  in  order 
to  make  them  rigid. 


CHAPTER  VI. 


SPECIALTIES  C ONTTtf UE D .  DAEK-E O OM. 

The  chamber  intended  for  all  operations  of  sensitizing, 
commonly  called  the  Dark-Room,  ought  to  lie  contiguous  to 
and  open  into  the  common  operating  or  work-room  of  the 
photographer ;  and  both  these  rooms  ought  to  open  di- 
rectly into  the  glass-house.  As  before  recommended,  they 
can  be  constructed  on  the  northern  aspect  of  the  gallery, 
each  being  seven  and  a  half  feet  wide — that  is,  half  the  width 
of  the  glass-room — and  about  ten  or  twelve  feet  long.  The 
work-room  may  be  that  on  the  left,  whilst  the  remaining  cham- 
ber is  on  the  right,  with  a  door  in  the  middle  of  the  parti- 
tion between  them.  A  single  pane  of  orange-yellow  colored 
glass  on  the  northern  end  is  all  that  is  needed  ;  this  window 
may  be  about  four  feet  from  the  ground,  in  order  that,  when 
the  operator  is  standing,  the  light  whilst  developing  may 
come  from  below  and  through  the  negative.  This  mode  of 
admitting  light  permits  the  progress  of  development  to  be 
distinctly  watched  much  more  effectively  than  by  reflected 
light.  The  elevation  of  the  pane  of  glass  above  the  floor 
must  be  regulated  in  accordance  with  the  stature  of  the 
operator  and  his  habits  of  standing  or  bending  during  the 
process,  so  that  sometimes  an  elevation  of  two  or  three  feet 
above  the  floor  of  the  room  will  be  found  sufficient.  The 
size  of  the  pane  will  be  adequately  large,  if  its  sides  are 
eight  inches  by  six,  and  a  dark-colored  curtain  is  adjusted 
over  this,  so  as  to  render  the  room  almost  dark  in  case  of 
need.  On  the  north,  east,  and  south  sides  a  shelf  is  con- 
structed twelve  inches  wide,  and  three  feet  from  the  floor. 
In  the  north-west  corner  the  pail  or  barrel  is  placed  to  con- 
tain water  for  washing  the  negatives  ;  this  pail  or  barrel  is 
supplied  with  a  brass  stop-cock,  such  as  is  used  for  beer  or 
wine  ;  beneath  the  stop-cock,  and  on  the  floor,  is  placed  the 
large  wash-tub  or  sink  for  containing  or  carrying  off  the  re- 
fuse dirty  water.  Beneath  the  north-west  and  the  north-east 
corner  there  will  be  found  abundance  of  space  for  the  gutta- 


SPECIALTIES  CONTINUED — D ARK-BOOM.  47 

perclia  developing  and  fixing  dishes,  as  also  for  the  respective 
solutions  used  in  these  processes,  and  for  intensifying,  as,  for 
instance,  protosulpliate  of  iron,  pyrogallic  acid,  cyanide  of 
potassium,  hyposulphite  of  soda,  solution  of  iodine  in  iodide 
of  potassium,  tincture  of  iodine,  nitrate  of  silver,  bichloride 
of  mercury,  and  sulphide  of  potassium.  Each  of  these  so- 
lutions must  be  legibly  labeled,  always  placed  in  the  same 
position,  and  always  carefully  corked.  As  regards  the  solu- 
tion of  the  sulphide  of  potassium,  the  necessity  for  accurate 
closing  of  the  bottle  which  contains  it  is  absolute,  because 
the  fumes  of  hydrosulphuric  acid,  if  allowed  to  escape  into 
the  room,  would  decompose  the  sensitizing-bath,  and  injure 
the  prints  and  negatives.  As  soon  as  a  negative  or  positive 
is  complete,  the  developing  and  fixing  solutions  are  poured 
back  into  their  respective  vials.  Care  must  be  taken  here 
also  not  to  interchange  dishes  ;  for  the  cyanide  of  potassium 
decomposes  the  iron-salt  into  what  soon  becomes  Prussian 
blue  by  oxidation  of  the  iron,  and  thus  renders  it  a  difficult 
task  to  clean  the  dish  afterward.  The  first  things  in  order 
on  the  eastern  shelf  are  the  plate-holders,  leaning  in  their  re- 
spective places  against  the  wall ;  after  this  comes  the  sen- 
sitizing-bath, on  an  inclined  frame  fixed  upon  the  shelf.  The 
inclination  may  be  about  fifteen  degrees  from  the  perpendic- 
ular ;  if  it  were  more  than  this,  the  light  particles  of  the 
undissolved  iodide  of  silver,  and  of  other  insoluble  sub- 
stances, would  be  apt  to  settle  upon  the  tender  surface  of  the 
collodion,  and  give  rise  to  apertures  in  the  negative.  To 
avoid  this  calamity  of  photographers,  it  is  preferable  to  have 
some  arrangement  by  which  the  collodionized  plate  can  be 
introduced  into  the  sensitizing-bath  with  its  collodion  sur- 
face downward.  For  this  purpose  flat  dishes  are  used  with 
a  glass  or  porcelain  ledge  on  the  right  side  to  support  one 
end  of  the  plate,  whilst  the  other'  end  rests  on  the  bottom 
of  the  dish  on  the  left  side.  In  this  way  the  left  end  of  the 
collodionized  plate  is  introduced  first  into  the  bath,  whilst 
the  right  end  is  gradually  and  quickly  lowered,  by  means  of 
a  silver  or  glass  hook,  until  it  comes  in  contact  with  the  ele- 
vated ledge  which  is  to  support  it.  The  plate  is  to  be  com- 
pletely covered  with  the  nitrate  of  silver  when  thus  lowered 
upon  its  support,  which  need  not  be  more  than  a  quarter  of 
an  inch  above  the  bottom  of  the  dish.  Naturally,  when  the 
plate  is  in  this  position,  the  collodion  is  nowhere  in  contact 
with  the  vessel  which  contains  it,  excepting  at  the  upper 
and  lower  edges.  By  making  the  above-mentioned  ledge 
still  more  shallow,  a  very  small  quantity  of  the  silver  solu- 


48 


SPECIALTIES  CONTINUED — DARK-ROOM. 


tion  will  suffice  to  cover  the  plate,  and  the  solution  can  be 
filtered,  if  necessary,  after  each  operation  ;  whereby  there 
can  be  but  small  risk  of  any  damage  from  the  deposition  of 
particles  of  undissolved  matter  upon  the  film  of  collodion. 
In  this  country,  the  vertical  or  slightly  inclined  sensitizing- 
baths  are  preferred,  and  consequently  in  most  general  use  ; 
in  France  and  Germany,  the  horizontal  baths  are  frequently 
to  be  met  with,  and  are  certainly  to  be  recommended  in 
order  to  avoid  the  trouble  above  alluded  to. 

To  the  right  of  the  silver-bath  for  collodion-plates  is  the 
appropriate  place  of  the  horizontal  dish  to  contain  the  sen- 
sitizing solution  for  the  chloridized  paper.  This  dish  will 
have  a  capacity  to  meet  the  requisitions  of  the  establish- 
ment, and  may  contain  a  whole  sheet,  a  half-sheet,  or  even 
less,  as  the  case  may  be.  Oil  a  small  shelf  two  feet  above 
this  dish  are  placed,  in  separate  bottles,  the  plain  silver  and 
the  ammonio-nitrate  of  silver  solutions,  a  small  filtering- 
stand  and  funnel,  ammonia,  alcohol,  and  distilled  water ;  and 
running  from  the  dish  to  the  southern  side  is  constructed  an 
inclined  plane  with  a  semicircular  groove  covered  or  lined 
with  plates  of  glass  or  porcelain,  each  one  overlapping  its 
fellow  like  tiles.  The  first  one  just  projects  over  the  edge 
of  the  dish.  This  grooved  inclined  plane  is  screwed  to  the 
eastern  side  of  the  room,  and  being  thus  tiled,  is  situated  in 
the  right  position  for  receiving  the  droppings  of  nitrate  of 
silver  from  the  sensitized  sheets  when  removed  from  the 
dish,  and  attached  by  pins  through  an  upper  angle  to  a  soft 
wooden  slip  immediately  above.  The  first  sheet  that  is 
taken  from  the  bath  is  fixed  at  the  most  distant  point,  and 
so  that  the  lowest  angle  is  just  in  contact  with  the  upper- 
most inclined  glass  tile ;  the  next  is  pinned  close  to  it,  until 
the  row  is  complete.  If  the  lower  corners  or  angles  of  the 
silvered  paper  touch  the  glass,  the  superfluous  fluid  will 
easily  flow  off  and  down  the  inclined  plane  into  the  dish ;  if 
the  corners  curl  up,  it  will  then  be  necessary,  with  a  small  A 
pad  of  cotton-wool  or  a  glass  rod,  to  remove  the  accumu- 
lated solution,  by  bringing  the  corner  in  contact  with  the 
grooved  channel.  By  this  arrangement  the  photographer  is 
able  to  economize  his  time  and  his  solution.  As  soon  as  one 
row  is  thus  filled  with  sensitized  papers,  those  first  pinned 
up  will  probably  be  sufficiently  dry  for  removal  to  another 
slip  situated  on  the  southern  side  of  the  dark-chamber,  thus 
making  room  for  a  fresh  quantity  of  papers. 

The  semicircular  grooves  of  glass  can  be  manufactured  as 
follows :  Take,  for  instance,  a  piece  of  iron  plate  about  fif- 


SPECIALTIES  CONTINUED  DARK-ROOM. 


49 


teen  inches  long  and  two  inches  wide,  and  get  it  hammered 
longitudinally  into  a  hollow  groove  ;  next  cut  up  slips  of 
glass  of  the  same  length,  and  about  an  inch  and  a  half  wide. 
Place  one  of  these  slips  of  glass  in  the  iron  channel  so  that 
it  lies  uniformly  in  the  middle.  Now  heat  the  iron  carefully 
red-hot,  when  it  will  be  found  that  the  glass  will  soften, 
sink,  and  assume  the  shape  of  the  mould.  When  this  has 
succeeded,  allow  the  iron  to  cool  gradually,  in  order  that 
the  glass  may  be  properly  annealed.  By  arranging  these 
cylindrical  glasses  so  that  they  overlap  each  other  about 
half  an  inch,  in  the  form  of  tiles,  there  is  no  need  of  apply- 
ing cement. 

WORK-ROOM. 

The  collodion  can  be  kept  on  a  small  shelf  in  the  dark- 
room, close  by  the  door,  in  a  very  convenient  place  to  seize 
when  occasion  requires.  With  this  convenience,  the  plates 
are  flowed  in  the  doorway  between  the  two  rooms.  At  the 
north  end  of  the  work-room  there  is  a  good,  large  window, 
with  the  lower  part  about  two  feet  from  the  floor,  flush  with 
the  upper  part  of  a  shelf  or  table  constructed  right  across, 
from  side  to  side.  On  the  sides  of  the  window-frame,  on 
nails  or  hooks,  hang  the  various-sized  mats  for  cutting  albu- 
men, etc.,  papers  or  photographs,  as  well  as  the  different- 
sized  plate-holders,  diaphragms,  pliers,  scissors,  diamonds, 
rulers,  brushes,  pencils,  etc.,  used  in  mounting,  printing,  etc. 
On  the  left  side  of  the  table,  on  small  shelves,  are  kept  acetic 
acid,  nitric  acid,  hydrochloric  acid,  sulphuric  acid,  protosul- 
phate  of  iron  in  crystals,  distilled  or  rain-water,  citric  acid, 
pyrogallic  acid,  alcohol,  pestle  and  mortar,  stirring-rods  of 
glass,  weights  and  scales,  graduated  measure  for  drachms 
and  ounces,  another  for  minims  and  drachms,  cyanide  of 
potassium,  hyposulphite  of  soda,  gun-cotton,  iodide  and  bro- 
mide of  cadmium,  iodide  and  bromide  of  ammonium,  nitrate 
of  silver,  ammonia,  chloride  of  ammonium,  gum-arabic,  ge- 
latine, solution  of  gum-arabic,  etc.,  brush,  spatula,  and  bur- 
nishing-tool,  carbonate  of  lime,  chlorinetted  lime,  acetate 
of  soda,  phosphate  of  soda,  iodine,  iodide  of  potassium, 
bromide  of  potassium,  bichromate  of  potassa,  and  other 
chemical  materials  for  experimentation.  The  preceding  ar- 
ticles have  to  be  arranged  on  narrow  shelves  in  the  order  in 
which  they  can  be  most  conveniently  laid  hold  of,  accord- 
ing to  their  respective  merits  as  necessary  or  accessory  in- 
gredients. On  the  right  side  of  the  window  arrange  the 
various-sized  glasses,  already  cut,  bath  for  negatives  and 
3 


50 


SPECIALTIES  CONTINUED — DARK-ROOM. 


positives,  the  patent  plate-holder  or  vice  for  cleaning  glass 
plates,  rotten-stone,  alcohol,  solution  of  salts  of  tartar,  dilute 
solution  of  nitric  acid,  cotton  or  linen  rags,  patches  of  Can- 
ton-flannel, silk  cloths,  broad  camel-hair  pencil  for  dusting  off 
particles  or  fibers  from  the  polished  glasses,  triangular  file, 
alcohol-lamp,  shell-lac  for  mending  the  glass-corners,  box  of 
pins,  box  of  tacks,  small  hammer,  large  and  thick  glass 
plate  for  cutting  out  photographs,  etc.,  scale  and  compasses, 
vignette-glasses,  the  different-sized  printing-frames,  varnish, 
mats,  preservers,  cases,  transfer-liquid,  leather,  black  paper 
or  velvet,  etc.,  mounts  of  various  sizes. 

The  sides  of  this  room  are  furnished  with  wooden  strips 
to  which  photographs  can  be  attached  by  pins  in  order  to 
dry  them  after  fixation  and  washing.  The  toning  and  fix- 
ing dishes  are  situated  on  the  shelf  on  the  west  side ;  as  are 
also  the  chloride  of  gold,  test-paper,  nitrate  of  uranium, 
acetate  and  phosphate  of  soda,  rain-water,  alcohol,  and 
hyposulphite  of  soda.  Beneath  the  shelf  place  the  tubs  for 
washing  prints.  In  drawers  preserve  the  different  sorts  of 
paper  in  use.  Have  one  drawer  for  dry  but  uncut  positives, 
one  for  the  cut  positives,  one  for  uncut  stereographs,  one  for  the 
right  stereographs  and  one  for  the  left,  one  for  card-pictures 
not  cut,  and  one  for  the  prepared  card-pictures.  One  writ- 
ing-desk near  the  door  and  between  the  door  and  the  win- 
dow, for  containing  the  day-book,  etc.  Photographic  stock 
can  be  stored  away  on  shelves  on  the  southern  end  and  on 
the  sides  of  this  room.  Both  these  rooms  are  to  be  supplied 
with  stoves  or  other  means  of  warmth  and  ventilation.  On 
the  entrance-door  affix  the  sign  forbidding  all  intrusion. 
Keep  all  visitors  in  the  antechamber,  which  must  be  made 
comfortable,  and  somewhat  artistically  furnished  for  their 
reception.  The  photographer  can  not  perform  his  duties 
Avith  ease  if  crowded  with  inquisitive,  meddling,  and  talking 
parties ;  the  lenses  do  not  operate  well  if  the  air  is  saturated 
with  vapor,  and  the  health  is  impaired  in  the  midst  of  the 
mixed  effluvia  arising  from  degenerate  lungs. 


CHAPTER  VII. 


COLLODION". 

In  1851  Legray  first  suggested  the  application  of  collodion 
for  the  receptacle  of  the  photographic  picture  ;  and  in  the 
same  year  Messrs.  Archer  and  Fry  published  a  detailed  ac- 
count of  the  practical  mode  of  its  application.  Collodion  is 
a  solution  of  gun-cotton  in  ether  and  alcohol ;  and  gun-cot- 
ton, of  which  there  are  several  varieties,  is  cotton  or  linen 
fiber  (that  is,  cellulose  or  lignine)  altered  by  combination 
with  peroxide  of  nitrogen  and  probably  with  nitric  acid. 
Cotton  consists  chemically  of  carbon,  hydrogen,  and  oxygen ; 
whilst  gun-cotton  contains  an  additional  element,  namely, 
nitrogen,  which  communicates  explosive  tendencies  to  several 
of  the  metalloids.  The  altered  cotton  employed  for  photo- 
graphic purposes  is  not  the  same  as  gun-cotton  proper  ;  in 
the  first  place  it  is  not  so  explosive ;  it  is,  secondly,  almost 
perfectly  soluble  in  alcohol  and  ether,  which  is  not  the  case 
with  gun-cotton.  It  is  denominated  pyroxyline.  Pyroxy- 
line  is  soluble  also  in  acetic  ether.  When  this  soluble  cot- 
ton is  dissolved  in  a  mixture  of  ether  and  alcohol,  and  after- 
ward poured  upon  a  piece  of  glass,  it  leaves  on  evaporation, 
when  of  a  normal  condition,  a  transparent  film ;  whereas 
gun-cotton  so  dissolved,  or  xyloidine,  (another  form  of  altered 
cotton,)  leaves  an  opaque  film  after  evaporation. 

Cotton  or  ligneous  fiber  is  transformed  into  pyroxyline  by 
immersing  it  in  a  mixture  of  nitric  acid  and  sulphuric  acid  ; 
the  latter  seems  necessary  only  to  concentrate  the  nitric  acid ; 
for  neither  sulphur  nor  any  of  its  oxides  are  found  in  pyroxy- 
line by  analysis.  This,  although  the  accepted  theory,  is  not 
satisfactory,  because  it  is  found  necessary  to  add  water  to 
certain  specimens  of  nitro-sulphuric  acid.  Another  reason 
for  the  use  of  sulphuric  acid  arises  from  the  fact  that  pyroxy- 
line is  soluble  into  a  gelatinous  form  in  nitric  acid,  but  not 
in  the  mixture  of  nitric  and  sulphuric  acids.  Gun-cotton 
may  be  precipitated  from  its  ethereal  and  alcoholic  solution 
into  a  fibrinous  mass  like  the  original,  almost.    This  curious 


52 


COLLODION. 


fact  exhibits  quite  an  analogy  between  solutions  of  salts  and 
the  mineral  kingdom,  and  the  gelatinous  solutions  in  the 
organic  kingdom.  In  the  former  the  precipitate  is  either 
amorphous  or  crystalline,  as  in  chloride  of  silver  and  ear- 
bozotate  of  potassa  ;  whilst  in  organic  solutions  the  precip- 
itated ultimate  atoms  seem  to  exist,  even  in  solution,  in  the 
form  of  fiber.  This  peculiar  fibrinous  deposit  is  thrown 
down  by  adding  water  to  the  mixed  ethereal  and  alcoholic 
solution  of  pyroxyline,  because  this  substance  is  insoluble  in 
water.  For  this  reason  the  necessity  of  using  only  concen- 
trated ether  and  alcohol  is  apparent ;  another  deduction  is 
equally  apparent  from  this  circumstance,  which  consists  in 
the  employment  of  such  iodizing  materials  in  the  prepara- 
tion of  sensitive  collodion,  as  are  soluble  in  ether  and  alco- 
hol, and  in  discarding  those  which  are  soluble  principally  in 
water,  or  only  partially  in  ether  and  alcohol.  Collodion 
containing  a  small  proportion  of  water  is  thick  and  flows 
unevenly,  and  when  dry  is  not  quite  transparent ;  whilst  the 
film  from  anhydrous  collodion  is  very  thin,  transparent,  and 
uniform,  and  flows  on  the  surface  of  glass  very  easily. 

Preparation  of  Pyroxyline. — For  this  purpose  the  finest 
cotton  or  the  best  Swedish  filtering-paper,  or  old  white  cotton 
rags  are  procured.  These  materials,  especially  the  first,  are 
not  quite  pure  ;  a  sort  of  resinous  cement  adheres  with  great 
tenacity  to  its  fibers,  and  must  first  be  dissolved  before  the 
cotton  is  fit  for  transformation  into  pyroxyline.  The  cotton 
is  therefore  boiled  in  a  solution  of  carbonate  of  potassa  in 
the  following  proportion :  take  one  hundred  parts  of  rain- 
water, two  parts  of  cotton,  and  one  of  carbonate  of  potassa. 
These  materials  are  maintained  at  a  boiling  temperature  for 
a  few  hours,  after  which  the  cotton  is  taken  out  and  thor- 
oughly washed  in  several  waters,  and  then  left  in  clean 
rain-water  for  at  least  twenty-four  hours,  stirring  the  same 
from  time  to  time;  until  every  trace  of  the  alkali  is  removed. 
It  is  then  taken  out,  pressed,  and  dried  in  thin  layers  spread 
upon  clean  sheets  of  paper  in  the  sun  or  on  a  steam-bath. 
Care  must  be  taken  that  all  moisture  be  entirely  expelled. 
In  this  condition  it  is  ready  for  the  action  of  nitric  acid. 
Certain  rules  have  to  be  minutely  observed  in  regard  to  the 
temperature  of  the  nitric  acid,  the  quantity  of  water  which 
it  contains,  the  length  of  time  of  immersion,  and  the  inti- 
mate mixture  of  the  ingredients  ;  for  as  these  conditions  vary 
so  will  the  pyroxyline.  If,  for  instance,  the  acids  are  too 
strong,  or  the  temperature  too  low,  the  pyroxyline  will  be 
much  heavier  than  the  weight  of  the  cotton  used,  without 


COLLODION. 


53 


apparently  having  undergone  any  other  outward  change. 
Such  gun-cotton  will  produce  a  thick  and  gelatinous  collo- 
dion, giving  rise  to  streaks  in  the  film.  If,  on  the  contrary, 
the  resulting  pyroxyline  is  less  in  weight  than  the  cotton 
introduced,  or  about  equal  to  it,  this  indicates  that  the  acids 
are  too  weak  or  the  temperature  too  high,  whereby  a  portion 
of  the  pyroxyline  is  dissolved.  Such  a  species  of  gun-cotton 
is  not  wholly  soluble  in  a  mixture  of  ether  and  alcohol ;  it 
yields,  however,  a  collodion  which  flows  easily  over  the 
plate,  is  very  adhesive  to  the  glass,  and  yields  a  soft  nega- 
tive. Any  little  particles  of  dust  that  may  fall  on  the  plate 
are  liable  to  produce  with  this  collodion  transparent  specks 
on  the  positive  or  negative.  The  rule,  therefore,  on  the 
wThole  is  to  steer  between  these  two  results,  in  order  to  ob- 
tain a  pyroxyline  in  which  the  cotton  fiber  shows  an  incipi- 
ent gelatinization  in  the  acids.  When  the  operation  is  suc- 
cessful, the  weight  of  the  dry  pyroxyline  will  be  somewhere 
about  twenty-five  per  cent  heavier  than  the  cotton  from 
which  it  was  formed. 

JSTo.  1.  Formula  for  the  Preparation  of  Pyroxyline. 

Commercial  sulphuric  acid,  spec,  grav.,  1.843  at  60  Fahr.,.  .24  fluid  ounces. 
Commercial  nitric  acid,         "       "     1.457  u  "     "    . .  8    11  " 

Water,   1    "  " 

Cotton,   1  ounce. 

The  vessels  used  in  the  preparation  of  pyroxyline  may  be 
large  porcelain  or  glass  evaporating-dishes,  sitting  closely  in 
the  cover  of  a  water-bath,  maintained  at  a  temperature  of 
150°  Fahrenheit.  Each  dish  is  furnished  with  a  pane  of 
glass,  fitting  upon  it  as  a  lid  or  cover.  Let  the  water-bath 
be  first  raised  to  the  indicated  temperature ;  then  pour  the 
sulphuric  acid  into  one  of  the  dishes,  add  to  this  the  water,  and 
mix  intimately  by  stirring  with  a  glass  rod  with  a  rounded 
end ;  finally  pour  in  the  nitric  acid,  and  perform  the  same 
operation  to  insure  an  intimate  mixture.  The  temperature 
of  this  mixture  will  rise  from  15  to  20  degrees  above  the 
point  required.  Remove  the  dish,  therefore,  from  the  bath 
until  the  temperature  falls  to  150°.  The  temperature  can 
be  lowered  by  stirring  the  mixture  with  cold  stirring-rods  or 
spatulas  of  porcelain  or  glass.  Whilst  the  acids  are  cooling 
the  cotton  can  be  divided  into  about  a  dozen  lots,  and  each 
lot  must  be  gently  separated  into  a  loose  condition.  As 
soon  as  the  proper  temperature  has  been  attained,  the  dish 
is  reinstated  in  its  position  in  the  water-bath,  and  the  cotton 
is  introduced  one  lot  at  a  time,  so  that  each  is  carefully 


54 


COLLODION. 


pressed  down  beneath  the  surface  by  the  glass  rod.  As 
soon  as  all  the  cotton  has  been  introduced  and  completely 
covered  by  the  acid  mixture,  the  lid  is  placed  on  the  dish 
for  six  or  eight  minutes. 

The  thermometer  used  on  such  occasions  for  ascertaining 
the  temperature  of  the  water  or  mixed  acids,  must  be  strong- 
ly made,  so  that  the  bulb  can  be  moved  about  in  the  fluid 
with  some  degree  of  briskness  without  any  liability  to  break ; 
it  is  furnished  with  a  hinged  back,  which  allows  the  lower 
portion  to  be  reflected  on  itself,  and  the  bulb  and  the  lower 
part  of  the  stem  to  be  exposed.  Such  thermometers  are 
manufactured  for  the  chemist,  and  can  be  purchased  at  the 
photographic  establishments. 

The  acids  are  now  poured  into  another  dish  close  by, 
allowing  the  largest  portion  to  drain  off,  and  preventing  the 
cotton  from  falling  out  at  the  same  time  by  the  cover  which 
is  retained  in  its  place.  The  dish  containing  the  pyroxyline 
is  then  quickly  immersed  in  a  large  tub  of  water,  and  the 
cotton  is  well  stirred  about  so  as  to  part  with  the  largest 
portion  of  its  acidity ;  it  is  then  taken  out  with  a  pair  of 
glass  rods  and  plunged  into  fresh  water  in  another  tub,  and 
again  thoroughly  washed.  After  this  operation  the  pyroxy- 
line is  placedin  a  wooden  chamber  through  which  a  current 
of  water  is  kept  running  for  twenty-four  hours  or  more,  or 
at  least  until  every  trace  of  acidity  has  been  removed.  Dur- 
ing this  time  the  agglutinated  or  adherent  portions  are  care- 
fully separated,  so  that  the  stream  of  water  can  more  easily 
act  upon  each  fiber.  When  blue  litmus  paper  is  no  longer 
turned  red  by  the  Avater  as  it  proceeds  from  the  cotton,  the 
latter  is  taken  out,  again  carefully  separated  and  placed  in 
thin  patches  on  sheets  of  paper  in  the  sun  to  dry ;  or  it  may 
be  dried  on  zinc  plates,  being  part  of  a  hot-water  bath, 
whose  temperature  is  maintained  at  about  120°  Fahrenheit. 
At  this  temperature  pyroxyline  will  not  explode.  In  the 
hot  days  of  summer,  however,  it  can  be  dried  quite  effica- 
ciously when  placed  out  in  the  sun. 

Pyroxyline,  when  exposed  to  the  air,  absorbs  moisture ;  it 
undergoes  decomposition,  too,  in  an  air-tight  vessel,  if  light 
reaches  it ;  the  products  of  decomposition  being  nitric  acid, 
peroxide  of  nitrogen,  and  probably  other  compounds.  It 
has  not  yet  been  thoroughly  ascertained  by  what  means  it 
can  be  preserved  in  a  normal  condition  permanently ;  ab- 
sence of  moisture  and  of  light  have  been  found  to  assist  in 
this  preservation. 


COLLODION. 


55 


If  a  specimen  of  pyrcxyline  by  keeping  manifests  an  acid 
reaction,  it  is  advisable  to  wash  the  cotton  in  several  waters, 
as  before,  and  again  to  dry  it.  To  neutralize  the  cotton  by 
an  alkali,  or  a  carbonated  alkali,  is  scarcely  to  be  recom- 
mended, because  they  both  have  a  tendency  to  decompose 
it ;  and  especially  if  any  trace  of  these  should  be  left  in  the 
fiber,  decomposition  is  likely  to  ensue  in  the  drying. 

No.  2.  Formula  for  the  Preparation  of  Pyroxyline. 


By  Weight. 

Commercial  sulphuric  acid,  spec,  grav.,  1.843,  at  60°  Fahr.,  18  ounces, 

Commercial  nitric  acid,         "       "      1.43,    "  "      "   14  " 

Cotton,   2  " 

Proceed  with  these  ingredients  in  all  other  respects  as 
with  those  in  Formula  No.  1. 

No.  3.  Formula  for  the  Preparation  of  Pyroxyline. 

Commercial  sulphuric  acid,  40  ounces, 

Pure  nitrate  of  potassa,  20  " 

Cotton,   1  ounce. 


As  soon  as  the  mixture  of  acid  and  nitre  has  been  thor- 
oughly mixed,  and  almost  cool,  the  cotton  is  introduced  in 
small  portions  and  well  stirred.  In  about  a  quarter  of  an 
hour  the  whole  mixture  is  thrown  into  a  large  tub  full  of 
water ;  in  this  way  the  pyroxyline  is  freed  as  much  as  possi- 
ble from  the  acid  ;  after  this  it  is  washed  in  warm  water, 
and  finally  in  a  running  stream,  as  in  Formula  No.  1. 

No.  4.  Formula  for  the  Preparation  of  Pyroxyline. 

Disderts  Pyroxyline. 

Sulphuric  acid,  4000  grains. 

Pulverized  pure  nitrate  of  potassa,  2000  44 

Place  these  in  a  glass  vessel  provided  with  a  close-fitting 
cover,  and  stir  them  intimately  together  with  a  glass  rod. 
Next  add  150  grains  of  fine  cotton-wool,  in  small  flocks  at  a 
time,  and  immerse  them  thoroughly  with  the  glass  rod. 
When  all  the  cotton  has  been  introduced,  close  the  vessel 
and  set  it  aside  for  ten  or  fifteen  minutes.  After  this,  the 
pyroxyline  is  withdrawn  by  means  of  a  pair  of  glass  rods, 
and  well  washed,  as  before  recommended,  and  dried. 

In  all  these  formulas  the  acids,  when  once  used,  can  not 
be  employed  a  second  time ;  by  distillation,  the  nitric  acid 


56 


COLLODION. 


that  has  not  been  decomposed  might  be  obtained  and  used 
over  again,  if  other  combinations  and  decompositions  did 
not  result  from  the  application  of  so  high  a  temperature. 
In  general  the  mixture  is  regarded  as  useless,  and  thrown 
away. 


CHAPTER  VIII. 


ETHER    AND  ALCOHOL. 

The  next  ingredients  employed  in  the  manufacture  of 
plain  or  normal  collodion  are  alcohol  and  ether.  Both 
these  substances  belong  to  a  group  of  hydrocarbons  whose 
basic  compound  radical,  although  hypothetical,  is  denomin- 
ated ethyle,  consisting  of  four  equivalents  of  carbon  com- 
bined with  five  of  hydrogen,  and  represented  in  symbols  by 
C4  H5.  Ether  is  the  oxide  of  this  base,  and  alcohol  the  hy- 
dra ted  oxide  ;  that  is,  chemically  regarded,  the  only  differ- 
ence between  ether  and  alcohol  is,  that  the  latter  contains 
one  equivalent  of  water,  constitutionally  combined,  which  is 
wanting  in  ether.  The  hypothetical  compound  base,  ethyle, 
enters  into  combination  with  several  of  the  alkaloids  and 
acids,  giving  rise  to  distinct  chemical  combinations.  This 
fact  will  lead  us  to  seek  a  clue  for  various  untoward  and, 
as  yet,  unaccountable  phenomena  in  the  constitution  of  sensi- 
tized collodion,  and  its  frequent  want  of  permanency. 

Ethyle  Group. 

Ethyle,  Sijrribol  Ae,  C4  H5.      Cyanide  of  ethyle,  Ae  Cy. 

Oxide  of  ethyle,  (ether,)  Ae  0.        Nitrate  of  the  oxide  of  ethyle,.  .Ae  0,  N05. 

Hydrated  oxide  of  ethyle,  (alcohol,).  Ae  0,  HO.  Nitrite  of  the  oxide  of  ethyle,.  .Ae  0,  NOs. 

Bromide  of  ethyle,  Ae  Br.       Oxalate  of  the  oxide  of  ethyle,  .Ae  O,  C-2  63. 

Chloride  of  ethyle,  Ae  CI.       Hydride  of  ethyle,  Ae  H. 

Iodide  of  ethyle,  Ae  I.         Zinc  ethyle,   .  Ae  Zn,  etc. 

Some  of  the  compounds  of  the  ethyle  series  are  crystalliz- 
able  salts  ;  but  the  most  of  them  are  volatile  aromatic  fluids, 
denominated  ethers. 

Although  an  equivalent  of  water  is  the  only  difference 
between  alcohol  and  ether,  yet  no  direct  means  have  yet 
been  discovered  whereby  an  atom  of  water  can  be  so  com- 
bined with  ether  as  to  form  alcohol,  nor  abstracted  from  al- 
cohol constitutionally  so  as  to  leave  ether.  It  is  supposed, 
therefore,  that  the  elements  that  enter  into  the  formation  of 
ether,  and  water  and  ether,  owe  their  difference  to  a  differ- 
ence in  the  grouping  of  the  elementary  atoms. 
3* 


53 


ETHER  AND  ALCOHOL. 


ETHER. 

Ether,  sometimes  denominated,  but  very  wrongly,  sul- 
phuric ether,  is  obtained  by  decomposing  alcohol  by  means 
of  sulphuric  acid.  One  method  consists  in  the  distillation 
of  equal  weights  of  rectified  alcohol  (spec.  grav.  .835)  and 
sulphuric  acid.  As  soon  as  ebullition  commences,  a  color- 
less and  highly  volatile  liquid  passes  over  and  is  condensed 
into  a  receiver  surrounded  with  ice  or  snow.  This  method 
is  far  from  being  a  profitable  one  ;  for  at  a  temperature  be- 
low 260°  Fahr.  alcohol  distils  over;  and,  if  the  heat  be  greater 
than  310°,  another  of  the  numerous  hydrocarbons,  olefiant 
gas,  is  generated,  together  with  other  gaseous  and  liquid 
bodies.  By  a  second  method  the  sulphuric  acid  is  main- 
tained at  a  temperature  of  about  300°  Fahr.,  and  a  stream 
of  alcohol  is  made  to  enter  the  acid  gradually.  In  this  way 
a  large  quantity  of  alcohol  becomes  converted  into  ether. 
There  are  two  stages  in  the  preparation  of  ether ;  by  one  an 
impure  and  crude  ether  is  the  result ;  by  the  latter  the  ether 
is  rectified.    The  minutiae  are  as  follows : 

Take  of  alcohol  four  pints ;  sulphuric  acid,  one  pint ; 
potassa,  six  drachms;  distilled  water,  three  fluid  ounces. 
Add  gradually  fourteen  fluid  ounces  of  the  acid  to  two  pints 
of  the  alcohol  in  a  tubulated  retort,  and  shake  frequently  in 
order  to  produce  an  intimate  mixture.  Connect  the  retort 
when  placed  on  a  sand-bath  with  a  proper  condensing  ap- 
paratus, furnished  with  a  long  connecting-tube,  so  as  to  re- 
move the  vapors,  if  any  should  escape,  as  far  as  possible 
from  the  flame.  Explosions  are  very  apt  to  take  place  in 
the  preparation  of  ether,  unless  great  caution  be  taken. 
The  temperature  is  now  raised  quickly  until  ebullition  com- 
mences. As  soon  as  half  a  pint  of  ether  has  distilled  over, 
the  remainder  of  the  alcohol  previously  mixed  with  two 
fluid  ounces  of  the  acid  is  allowed  to  enter  gradually  through 
the  tubulated  aperture  by  means  of  a  tube  dipping  beneath 
the  mixture  in  the  retort,  and  in  quantity  as  near  as  can  be 
equal  to  that  which  distills  over.  In  this  way  continue  the 
distillation  until  about  three  pints  have  passed  over  into  the 
condenser. 

The  product  thus  obtained  contains  sulphurous  acid,  sul- 
phuric acid,  sulphovinic  acid,  and  other  impurities.  By 
rectification  most  of  these  are  removed  as  follows : 

Add  to  the  ethereal  contents  in  the  condenser  the  solution 
of  the  potassa  in  the  distilled  water,  and  shake  them  fre- 
quently during  the  twenty-four  hours  they  are  kept  together 


ETHER  AND  ALCOHOL. 


59 


in  a  stoppered  bottle.  After  subsidence  separate  the  super- 
natant ethereal  solution  by  means  of  a  syringe,  and  distill  off 
two  pints  of  this  solution  at  a  low  and  gentle  heat.  The 
specific  gravity  at  this  stage  will  be  about  .750.  By  further 
rectification  over  newly  burnt  quicklime  and  chloride  of  cal- 
cium, ether  may  be  obtained  of  a  specific  gravity  of  .720,  or 
even  lower.  When  perfectly  pure  its  specific  gravity  is  .713, 
and  it  boils  at  95°.  The  sulphuric  ether  of  commerce  is  not 
sufficiently  concentrated  for  photographic  purposes ;  and 
none  can  be  relied  upon  excepting  that  which  is  obtained 
direct  from  establishments  that  prepare  chemical  ingredients 
for  the  photographer.  When  the  specific  gravity  is  .720, 
ether  boils  at  98°  ;  this  is  the  kind  which  is  generally  used 
in  the  preparation  of  collodion.  When  too  long  kept  it  un- 
dergoes decomposition,  being  converted  partially  into  acetic 
acid.  It  is  a  very  important  solvent  of  oils,  resins,  and  al- 
kaloids, and  certain  metalloids,  as  iodine,  bromine,  sulphur, 
and  phosphorus.  It  does  not  dissolve  potassa  and  soda,  a 
very  distinct  characteristic  from  alcohol.  It  unites  in  all 
proportions  with  alcohol  and  with  one  tenth  its  volume  of 
water.  The  impurities,  as  before  mentioned,  are  acids,  al- 
cohol, water,  and  oil  of  wine.  The  presence  of  acids  are 
shown  by  litmus  ;  alcohol  combines  with  water  when  added 
in  excess,  and  settles  and  forms  the  lower  stratum ;  by  de- 
cantation  the  upper  stratum  is  removed,  which  now  contains 
one  tenth  its  weight  of  water  ;  water  is  removed  by  distilla- 
tion from  fresh  chloride  of  calcium ;  the  acids  by  distillation 
from  lime  or  potassa ;  the  oil  of  wine  is  shown  by  the  pro- 
duction of  a  milkiness  when  mixed  with  water. 


ALCOHOL. 

Alcohol  is  the  rectified  spirit  of  wine  of  the  specific  gravi- 
ty of  0.835,  containing  eighty-five  parts  of  anhydrous  alco- 
hol and  fifteen  of  water.  When  pure  and  anhydrous  it  is 
the  hydrated  oxide  of  ethyle,  (Ae  O,  HO.)  It  contains  six 
equivalents  of  hydrogen,  four  of  carbon,  and  two  of  oxygen— 
H6  C4  02.  All  sacc?iarine  substances  undergoing  vinous  fer- 
mentation give  rise  to  the  vapors  of  alcohol,  which  by  dis- 
tillation are  obtained  in  a  separate  and  more  concentrated 
form.  By  the  vinous  fermentation  sugar  is  converted  wholly 
into  alcohol  and  carbonic  acid  ;  and  it  is  only  from  sugar,  or 
substances  which  by  chemical  processes  are  converted  into 
sugar,  that  the  vinous  exhalation  can  be  obtained.  The  or- 
dinary alcohol  of  commerce  is  not  sufficiently  concentrated 


CO 


ETHER  AND  ALCOHOL. 


for  the  purposes  of  the  photographer,  because  the  water 
which  it  contains  would  precipitate  a  solution  of  pyroxyline, 
or  produce  an  opaque  solution.  Like  ether,  therefore,  it  has 
to  undergo  a  process  of  concentration.  Whisky  is  the  spirit 
from  which  the  first  alcohol  is  obtained,  which  contains 
water,  a  peculiar  oil,  and  extractive  matter.  By  distilling  a 
hundred  gallons  of  whisky,  between  fifty  and  sixty  gallons 
of  alcohol  are  received  in  the  condenser  of  a  specific  gravity 
of  0.835.  By  a  second  distillation,  taking  care  to  collect 
only  the  first  portions  and  cautiously  managing  the  heat,  so 
as  not  to  allow  it  to  rise  to  the  temperature  of  boiling  water, 
alcohol  may  be  obtained  of  a  specific  gravity  of  0.825,  which 
is  the  lightest  spirit  that  can  be  received  by  ordinary  dis- 
tillation. At  this  stage  it  contains  eleven  per  cent  of  water 
and  some  small  portions  of  fusel  oil. 

The  process  by  which  most  of  the  remaining  water  is 
separated  from  the  alcohol  is  as  follows  : 

Take  one  gallon  of  the  alcohol  of  commerce  ;  chloride  of 
calcium,  (freshly  made,)  one  pound.  Throw  the  chloride 
into  the  alcohol  and,  as  soon  as  it  is  dissolved,  distill  off 
seven  pints  and  five  fluid  ounces.  Or,  take  of  rectified 
spirit  one  pint,  (imp.  meas. ;)  lime,  eighteen  ounces.  Break 
the  lime  into  small  fragments,  mix  with  the  alcohol  in  a  re- 
tort properly  connected,  and  expose  the  mixture  to  a  gentle 
heat  until  the  lime  begins  to  slake ;  then  withdraw  the  heat 
until  the  slaking  is  finished.  ISTow  raise  the  heat  gently  and 
distill  off  seventeen  fluid  ounces.  Alcohol  thus  obtained  will 
have  a  density,  when  the  operation  is  carefully  managed,  of 
0.796. 

Neither  of  the  preceding  fluids,  taken  separately,  dissolves 
pyroxyline,  a  mixture  of  the  two  is  required  to  perform  this 
operation ;  the  proportion  in  which  they  exist  in  this  mix- 
ture, in  order  to  attain  to  the  maximum  degree  of  photo- 
graphic excellence,  is  a  problem  which  has  not  yet  been 
absolutely  solved.  When  there  is  a  large  excess  of  ether 
over  the  alcohol,  the  former  menstruum  will  easily  dissolve 
from  one  to  one  and  a  half  per  cent  of  the  prepared  cot- 
ton ;  and  this  proportion  will  scarcely  exceed,  under  the 
most  favorable  conditions,  from  two  to  three  per  cent  with- 
out producing  a  precipitate  in  the  solution.  On  the  con- 
trary, if  the  alcohol,  in  its  purest  state,  exists  in  the  mix- 
ture in  greater  quantity  than  the  ether,  three  per  cent  of 
pyroxyline  is  easily  dissolved,  producing  a  collodion  of  the 
proper  consistency ;  the  mixture,  however,  will  dissolve 


ETHER  AND  ALCOHOL. 


61 


from  eight  to  ten  per  cent  without  producing  any  deposit  in 
the  collodion. 

The  property  of  ether  in  collodion  is  to  communicate  te- 
nacity to  the  film,  which,  owing  to  the  excess  of  this  fluid, 
frequently  peels  off  from  the  glass  in  one  adherent  sheet ; 
beside  this,  ether  is  more  liable  to  decomposition  than  alco- 
hol, and  is  perhaps  one  of  the  causes  of  the  want  of  perma- 
nency in  collodion,  although  most  probably  pyroxyline  is  the 
principal  cause.  This  want  of  stability,  even  in  normal  col- 
lodion, is  increased  by  the  quantity  of  air  contained  in  the 
same  vessels,  giving  rise  to  an  ethereal  effluvia  which  it  did 
not  possess  before.  This  decomposition  is  much  more  rajoid 
when  the  collodion  is  exposed  to  light. 

Decomposition  of  Collodion. — The  decomposition  of  nor- 
mal or  plain  collodion  is  a  fact  that  can  easily  be  verified  ; 
but  experience  shows  also  that  the  iodides  and  bromides 
when  dissolved  in  pure  alcohol  and  ether  are  not  decom- 
posed, or  at  any  event  in  a  very  trifling  degree,  when  pro- 
perly protected  in  accurately  closed  bottles  ;  the  fluid  does' 
not  change  color  materially,  nor  does  it  show  the  presence 
either  of  free  iodine  or  bromine  ;  furthermore  the  solutions 
in  question,  when  kept  for  any  length  of  time,  produce  the 
same  sensitive  effects  on  plain  collodion. as  if  they  were 
freshly  made.  The  decomposition  in  collodion  does  not 
seem,  therefore,  to  be  superinduced  by  ether,  alcohol,  the 
iodides,  or  the  bromides;  for  each,  taken  separately  or  in 
combination,  when  pure  and  properly  protected,  is  not  liable 
to  any  perceptible  decomposition.  But  Van  Monckhoven 
maintains,  and  all  photographers  are  aware  of  the  fact,  that 
there  is  a  very  perceptible  difference  between  freshly-made 
plain  collodion  and  old  plain  collodion.  The  difference  is 
this  :  if  a  plate  be  coated  in  newly-made  plain  collodion  and 
then  immersed  in  a  solution  of  nitrate  of  silver  and  exposed 
before  an  object,  and  afterward  submitted  to  the  action  of 
the  developing  fluid,  no  traces  of  the  picture  will  appear ;  on 
the  contrary,  if  the  plain  collodion  be  old,  and  a  plate  be 
treated  with  this  as  in  the  preceding  case,  the  film  will  be 
whitened  by  the  sensitizing  solution,  and  will  be  sensitive  to . 
the  action  of  light  when  exposed  before  an  object,  and  will 
yield  a  picture.  A  second  difference  is  this :  the  collodion, 
before  thick  and  consistent,  becomes  thinner  and  exhales  an 
odor  of  nitric  ether  as  it  grows  older. 

Such  being  the  case,  it  seems  evident  that  the  pyroxyline 
is  the  cause  of  the  decomposition,  or  that  the  pyroxyline 


62 


ETHER  AND  ALCOHOL. 


contains  sometimes  extraneous  matter  that  produces  this  de- 
composition ;  and  when  the  change  has  once  set  in,  the  new- 
ly formed  bodies  may  react  upon  the  iodides  or  bromides 
when  introduced,  and  tend  to  produce  a  variety  of  decom- 
positions according  to  the  facility  or  difficulty  with  which 
they  undergo  change. 

But  the  next  question  is :  What  are  the  differences  be- 
tween freshly-made  iodized  collodion  and  an  iodized  collo- 
dion that  has  been  kept  long  ?    They  are  as  follows  : 

Firstly.  New  collodion  is  more  sensitive  to  light  than  old 
collodion. 

Secondly.  Although  more  sensitive,  it  produces  images 
which  are  much  less  intense  than  those  produced  by  old  col- 
lodion, that  is,  the  shadows  are  not  so  deep  or  black.  The 
images  are  mere  surface-pictures  when  developed  with  the 
sulphate  of  the  protoxide  of  iron. 

Thirdly.  If  the  plates  be  washed  after  sensitizing,  (in  the 
dry  process,)  when  freshly-made  collodion  is  used,  no  image 
will  appear ;  on  the  contrary,  with  old  collodion  the  washing 
does  not  prevent  the  picture  from  appearing. 

Fourthly.  The  shadows  of  the  picture  developed  by  the 
protosulphate  of  iron  are  entirely  soluble  in  nitric  acid  when 
a  freshly-made  collodion  is  used  ;  and  are  not  entirely  solu- 
ble with  an  old  collodion. 

Fifthly.  New  collodion  is  colorless,  or  nearly  so ;  whereas 
old  collodion  sometimes  is  as  deeply  red  as  a  strong  solution 
of  burnt  sugar. 

Sixthly.  New  collodion  has  the  odor  only  of  alcohol  and 
ether  ;  but  old  collodion  has  a  peculiar  ethereal  smell  resem- 
bling that  of  nitric  ether  and  aldehyde. 

We  are  indebted  to  Van  Monckhoven  for  the  summation 
of  these  differences  in  juxtaposition,  and  many  photographers 
will  recognize  the  truth  of  them. 

The  third  question  to  be  asked  is  then  the  following : 
What  substance  in  solution  will  communicate  to  recently 
prepared  iodized  collodion  the  properties  of  old  collodion  ? 
Hardwich  says  that  grape-sugar,  glycyrrhizine,  and  nitro- 
glucose  Avill  render  fresh  collodion  much  more  intense,  but 
that  they  diminish  its  sensitiveness.  Such  is  also  the  action 
of  the  substance,  be  it  what  it  may,  contained  in  altered 
collodion,  it  renders  collodion  more  intense  but  less  sensi- 
tive. 

Furthermore  Hardwich  remarks,  that,  if  these  substances 
be  employed  to  increase  the  intensity  of  the  shadows  in  the 


ETHER  AND  ALCOHOL. 


G3 


image,  they  ought  to  be  added  cautiously  because  they  de- 
teriorate from  the  keeping  properties.  But  nitro-glucose  is 
said  to  be  an  impurity  in  pyroxyline ;  it  is  analogous  in 
several  respects  to  pyroxyline  ;  and  it  is  prepared  with  sul- 
phuric acid,  nitric  acid,  and  sugar;  but  lignine  or  cellulose 
yields  sugar  when  treated  with  sulphuric  or  nitric  acid  ; 
hence  in  the  preparation  of  pyroxyline  grape-sugar  is  formed 
at  the  same  time,  and  by  the  further  action  of  the  acids, 
nitro-glucose  is  produced.  That  there  exists  a  duplex  com- 
pound in  collodion  may  be  shown  by  adding  water  to  it ;  a 
precipitate  will  be  formed,  of  which  one  part  is  fibrous  and 
the  other  gelatinous. 

But  the  identity  between  the  unknown  substance  and  ni- 
tro-glucose is  apparently  shown  by  the  identity  of  proper- 
ties. If  nitro-glucose  be  dissolved  in  alcohol,  it  forms  a 
colorless  solution  with  an  odor  of  alcohol,  which  has  no  effect 
at  this  stage  on  collodion,  nor  on  an  alcoholic  solution  of 
nitrate  of  silver ;  but,  after  the  expiration  of  a  few  days,  it 
assumes  a  rose-colored  tinge  and  the  odor  peculiar  to  old  col- 
lodion ;  furthermore,  at  this  second  stage,  it  now  communi- 
cates to  fresh  collodion  all  the  properties  of  old  collodion, 
and  forms  a  precipitate  in  nitrate  of  silver  in  alcohol.  Van 
Monckhoven  in  addition  has  convinced  himself  that  the  pre- 
cipitate formed  in  old  collodion  by  an  alcoholic  solution  of 
nitrate  of  silver  is  six  times  as  bulky  as  that  which  would 
be  the  result  from  the  iodide  of  silver,  and  that  its  proper- 
ties were  the  same  as  those  in  the  precipitate  formed  by 
mixing  the  rose-colored  nitro-glucose  with  alcoholic  nitrate 
of  silver. 

Preparation  of  Glycyrrhizine. — This  substance  is  obtained 
by  boiling  liquorice-root  in  water  for  some  time,  and  addiug 
sulphuric  acid  to  the  concentrated  syrup.  A  white  precipi- 
tate is  formed,  containing  glycyrrhizine,  albumen  and  sul- 
phuric acid.  The  albumen  is  removed  by  washing  the  pre- 
cipitate, first  in  acid- water,  then  in  water,  and  afterward  by 
solution  in  alcohol.  Carbonate  of  potash  is  then  added  to 
decompose  the  alcoholic  solution,  and  to  precipitate  the  sul- 
phuric acid.  By  evaporating  the  liquid,  glycyrrhizine  re- 
mains as  a  yellow,  transparent  mass. 

Preparation  of  Nitro-glucose. — Add  one  ounce  of  pow- 
dered sugar  to  a  mixture  of  two  fluid  ounces  of  sulphuric 
acid,  one  of  nitric  acid.  Stir  the  mixture  for  a  few  minutes 
with  a  glass  rod ;  a  tenacious  mass  may  thus  be  collected 
from  the  fluid,  and  washed  in  warm  water  by  kneading  it 
until  every  trace  of  acid  is  removed. 


64 


ETHER  AND  ALCOHOL. 


Collodion  iodized  with  the  ammonium  salt  is  the  least 
stable  ;  whilst  a  cadmium  collodion  is  the  most  permanent. 
Collodion  in  which  the  alcohol  is  in  larger  abundance  than 
the  ether  is  more  stable,  and  at  the  same  time  more  fluid ;  it 
adheres  well  to  the  glass,  forms  no  ridges  in  flowing,  and  is 
in  fact  quite  structureless. 


CHAPTER  IX. 


COLLODION  SENSITIZERS  IODIDES  AND  BROMIDES. 

The  salts  employed  for  sensitizing  plain  collodion  for  the 
reception  of  the  actinic  impression,  are  the  iodides  and  bro- 
mides of  different  metals,  as  of  potassium,  sodium,  ammo- 
nium, lithium,  zinc,  iron,  calcium,  cadmium,  etc. 

Iodides  and  bromides,  which  are  soluble  in  ether  and  al- 
cohol, can  alone  be  employed  in  the  preparation  of  sensitized 
collodion,  in  order  to  produce,  by  decomposition  in  and  on 
the  film,  an  iodide  and  a  bromide  of  silver,  which  are  insolu- 
ble. In  so  extensive  a  choice  of  materials  it  is  a  difficult 
matter  to  collect  all  the  advantages  of  a  given  iodide  or  bro- 
mide over  its  neighbors ;  so  that  it  has  not  yet  been  decided 
which  is  the  most  appropriate  iodide  or  bromide. 

If  each  soluble  iodide  or  bromide  were  equally  applicable 
in  a  photographic  sense,  then  the  choice  would  be  influ- 
enced by  pecuniary  considerations  of  cost  and  the  quantities 
required ;  and  if  by  weight  the  iodides  and  bromides  were 
equal  in  price,  the  selection  would  fall  upon  that  iodide  and 
bromide  whose  chemical  equivalent  is  the  least ;  for  the  less 
the  combining  proportion  of  a  given  chemical  substance,  the 
less  the  quantity  required  to  produce  a  given  effect.  Guided 
by  this  consideration  of  the  subject,  the  iodide  and  bromide 
of  lithium  would  claim  our  first  attention ;  after  lithium 
come  magnesium,  ammonium,  calcium,  sodium,  iron,  zinc, 
potassium,  cadmium,  etc.  The  solubility  of  the  respective 
iodides  and  bromides  in  a  mixture  of  ether  and  alcohol  will 
naturally  form  a  second  consideration  ;  and,  thirdly,  a  very 
important  property  must  have  its  due  weight  in  the  scales, 
and  that  is  the  stability  of  the  given  salt  in  the  ethereal  solu- 
tion. The  alkaline  iodides  and  bromides  are  all  soluble,  so 
that  lithium  stands,  perhaps,  quite  as  high  as  the  rest  in  this 
respect.  In  absolute  alcohol  the  iodide  of  potassium  is  not 
soluble  to  the  same  extent  as  iodide  of  ammonium.  The  lat- 
ter iodide  is  the  most  easily  decomposed.  On  this  account 
it  is  regarded  as  a  more  sensitive  iodizer ;  it  is  also  quicker ; 


66       COLLODION  SENSITIZERS  IODIDES  AND  BROMIDES. 

but  on  the  same  account  it  is  unstable  and  undergoes  spon- 
taneous decomposition.  The  iodide  of  ammonium,  as  well 
as  that  of  potassium,  is  very  capricious. 

The  bromide  of  silver  is  sensitive  to  light  as  well  as  the 
iodide  and  the  chloride  ;  but  the  spectral  rays  have  not  the 
same  influence  on  either  of  these  three  salts.  The  actinic 
impression  on  the  iodide  and  bromide  of  silver  is  invisible  or 
latent,  and  requires  the  aid  of  some  developing  agent  to 
make  manifest  the  effect  of  light;  whilst  the  impression 
made  on  the  chloride  of  silver  becomes  manifest  in  propor- 
tion to  the  intensity  and  duration  of  light. 

The  photographed  image  of  the  solar  spectrum  is  mucli 
broader  on  the  bromide  of  silver  film,  than  on  the  iodide 
film.  In  the  former  case,  the  violet,  the  indigo,  the  blue, 
and  partially  the  green  produce  actinic  action ;  whilst  in  the 
latter  the  blue  part  is  but  partially  represented.  Equal  por- 
tions on  the  violet  side  and  external  to  the  violet  color  pro- 
duce an  equal  impression  on  either  of  the  films.  The  greater 
capacity  of  the  bromized  film  has  induced  photographers  to 
attribute  to  bromine  qualities  specially  adapted  to  land- 
scape-photography, where  the  greens  occupy  so  large  a  space. 
By  the  introduction  of  the  bromides  into  collodion,  together 
with  the  iodides,  much  discussion  has  arisen  to  determine 
the  precise  action  of  the  former.  Certain  collodions  with 
certain  baths  are  acknowledged  to  undergo  an  improvement 
when  a  bromide  is  a  part  of  the  sensitizer ;  the  picture  is 
softened,  that  is,  the  middle  tints  are  more  pronounced,  or 
the  lights  and  shades  more  agreeably  graded  with  the  bromo- 
iodizer,  than  with  the  simple  iodizer.  On  this  account,  pro- 
bably, bromides  have  been  regarded  by  many  as  accelera- 
tors, or  substances  which  render  collodion  more  sensitive  to 
light.  On  this  ground  alone  the  deduction  would  be  false. 
The  capacity  for  comprehending  a  greater  range  of  colors  is 
possessed  by  the  bromo-iodized  collodions.  This,  perhaps,  is 
the  only  true  and  legitimate  deduction  that  can  be  drawn  in 
the  case ;  they  are  considered  by  very  high  authority,  on  the 
contrary,  as  deduced  from  experiments  carefully  conducted, 
to  be  retarders  of  the  actinic  action.  In  consequence  of  the 
greater  comprehensiveness,  as  regards  colors,  of  the  bro- 
mides over  the  iodides,  it  may  be  concluded,  that  there  are 
very  few  cases  in  which  the  bromo-iodized  collodion  can  not 
be  appropriately  preferred  to  the  simply  iodized  collodion  ; 
the  exceptions  being  the  copying  of  engravings,  plain  or  un- 
colored  photographs,  maps,  letter-press  printing,  etc.,  where 


COLLODION  SENSITIZERS  IODIDES  AND  BROMIDES.  67 

the  iodized  collodion  alone  possesses  all  the  capacity  re- 
quired. 

A  peculiarity  has  been  discovered  in  reference  to  iodized 
collodion.  Some  sorts  of  collodion  are  suitedfor  one  iodizer, 
and  some  for  another.  As  a  general  rule,  a  cadmium  iodide 
glutinizes  collodion ;  whereas  an  alkaline  iodide  liquefies  it. 
The  natural  deduction  from  these  circumstances  is  this :  a 
glutinous  or  tenacious  collodion  is  suited  for  sensitizing  with 
iodide  of  ammonium,  or  iodide  of  potassium ;  for  it  becomes 
thereby  less  tenacious,  and  flows  better.  Such  collodion 
soon  attains  its  maximum  amount  of  sensitiveness,  and  al- 
most with  the  same  facility  begins  to  deteriorate ;  it  is  very 
unstable,  and  not  permanent  in  any  degree  of  sensitiveness. 
On  the  other  hand  an  alcohol  collodion,  which  is  in  a  con- 
dition to  flow  easily,  is,  in  fact,  thin  and  liquid,  can  be  ren- 
dered more  glutinous  by  a  cadmium  iodide.  Collodion  thus 
iodized  is  much  more  stable  than  when  iodized  with  the 
alkaline  iodides,  but  it  attains  its  maximum  degree  of  sensi- 
tiveness very  slowly,  that  is,  it  takes  a  longer  time  to  ripen 
than  the  first-mentioned  collodion ;  but  when  ripe,  it  retains 
its  sensitiveness  much  longer,  is  in  fact  a  stable  collodion. 
Coupling  these  two  facts  together,  attempts  have  been  made 
to  combine  the  iodide  of  cadmium  with  an  alkaline  iodide  in 
such  proportions  as  to  comprehend  the  peculiar  advantages 
of  either,  that  is,  the  stability  and  permanency  of  the  one 
with  the  quick  sensitiveness  of  the  other,  and  the  mutual 
tempering  of  either  toward  a  medium  glutinosity  or  lique- 
faction. The  result  of  such  experiments  indicates  that  the 
cadmium  salt  must  exceed  the  alkaline  salt  in  quantity.  As 
soon  as  the  highest  degree  of  sensitiveness  and  stability  can 
be  established  by  means  of  the  iodides  alone,  it  remains  then 
to  combine  with  these  a  certain  proportion  of  a  bromide  to 
communicate  to  the  collodion  a  greater  capacity  for  colors. 
Notwithstanding  that  this  is,  in  my  opinion,  the  view  we 
have  to  take  of  the  matter,  it  must  be  confessed  that  the 
best  working  quantities  of  the  iodides,  or  of  the  bromo- 
iodides  have  not  yet  been  satisfactorily  determined.  The 
difficulty  that  stands  in  the  way  of  this  determination  is  in- 
creased by  the  peculiar  condition  of  the  nitrate  of  silver 
bath,  whether  it  be  acid,  neutral  or  alkaline ;  and  further- 
more whether  it  be  rendered  acid  by  nitric  acid  or  acetic 
acid ;  or  whether  it  contain  carbonate  of  soda  or  acetate  of 
soda.  A  cadmium  iodized,  or  bromo-iodized  collodion  sensi- 
tized in  a  bath  of  nitrate  of  silver  rendered  slightly  acid 
with  nitric  acid,  produces  irreproachable  pictures,  but  not 


68       COLLODION  SENSITIZERS — IODIDES  AND  BROMIDES. 

more  rapidly  than  a  bath  containing  acetic  acid,  acetate  of 
soda,  or  carbonate  of  soda,  when  these  happen  to  be  in  a 
happy  mood;  but  the  latter  are  very  unstable,  whilst  the 
former  remains  for  a  long  time  constant,  and  is  regarded  ac- 
cordingly the  proper  bath  for  the  cadmium  collodion.  It 
must  not  be  forgotten  that  acids  are  retarders  of  sensitive- 
ness, and  that  consequently  a  bath  that  yields  a  picture  with- 
out spots,  stains,  or  fogginess  is  preferable  in  the  ratio  as  it 
approaches  neutrality.  A  bath  containing  either  acetate  of 
soda  or  carbonate  of  soda  is,  when  in  its  best  condition,  an 
accelerator  ;  but  it  is  very  unstable,  deteriorates  very  quick- 
ly, and  at  present  no  means  are  known  to  rectify  the  evil 
and  preserve  or  restore  the  sensitiveness. 

The  iodides  and  bromides  most  generally  employed  by 
the  photographer  are  those  of  lithium,  potassium,  sodium, 
ammonium,  cadmium,  and  silver. 


CHAPTER  X. 


PREPARATION   OF  THE  IODIDES. 

Several  of  the  iodides  are  formed  by  the  direct  contact  of 
the  elements,  as,  for  instance,  the  iodide  of  iron  and  the 
iodide  of  phosphorus.  Others  by  double  decomposition,  as 
iodide  of  silver  from  a  soluble  iodide  and  nitrate  of  silver. 
And,  finally,  others  are  obtained  by  combining  chemical 
equivalents  of  hydriodic  acid  with  the  carbonates  of  the 
bases  required,  as,  for  example,  iodide  of  potassium  from 
hydriodic  acid  and  carbonate  of  potassa,  iodide  of  barium 
from  hydriodic  acid  and  carbonate  of  baryta,  etc.  Iodine 
or  hydriodic  acid  is  the  material  from  which  the  iodides  may 
be  and  are  prepared. 

Iodine. 

Symbol,  I.    Chemical  Equivalent,  127^^  ;  Specific  Gravity,  4.948. 

Iodine  was  discovered  in  1812,  by  Courtois,  a  chemical 
manufacturer  in  Paris.  This  substance  exists  in  nature  com- 
bined with  metals,  such  as  calcium,  magnesium,  and  sodium ; 
and  these  are  found  in  many  saline  springs  and  mineral  waters, 
as  also  in  sea-water.  These  salts  are  absorbed  by  several 
marine  plants  and  animals ;  and  it  is  from  such  plants  that 
iodine  is  obtained  in  considerable  abundance.  The  sea-plants 
are  collected,  dried,  and  burned  in  large  pits,  the  ashes  of 
which  are  called  kelp.  Formerly  this  kelp  was  collected  on 
account  of  the  carbonated  alkali  which  it  contains  ;  its  value 
now  is  enhanced  on  account  of  the  iodides  and  chlorides 
which  are  found  in  it.  The  powdered  mass  is  dissolved  in 
cold  water,  which  is  afterward  evaporated  until  a  scum  forms 
on  the  surface.  The  solution  is  then  set  aside  to  cool,  when 
a  quantity  of  crystals  will  be  deposited.  By  a  further  evap- 
oration, more  crystals  may  be  obtained,  until  finally  the 
mother-liquor  ceases  to  yield  any  more.  The  dark-colored 
liquid  contains  the  iodides,  which  may  be  precipitated  by  a 
mixture  of  five  parts  of  sulphate  of  iron  and  two  parts  of  sul- 
phate of  copper.  The  precipitate  is  subiodide  of  copper, 
which,  by  treatment  with  sulphuric  acid,  the  deutoxide  of 


70 


PREPARATION  OF  THE  IODIDES. 


manganese  and  heat,  yields  iodine  ill  violet  vapors,  which  by- 
condensation  form  the  metallic-looking  crystals  of  iodine. 
There  are  other  methods  of  separating  the  iodides. 

Properties. 

Iodine  resembles  plumago  or  black  lead,  in  outward  ap- 
pearance ;  it  is  a  crystalline  substance,  soft  and  brittle.  It 
melts  at  224°,  and  sublimes  at  347°.  Its  taste  is  very  acrid 
and  astringent ;  its  smell  is  somewhat  like  that  of  chlorine. 
Water  dissolves  about  one  part  in  seven  thousand  parts,  and 
receives  a  brown  color.  Alcohol  and  ether  dissolve  it 
abundantly;  and  so  do  iodide  of  potassium  and  hydriodic 
acid,  forming  brownish  red  solutions.  Iodine  in  solution,  as 
tincture,  or  in  iodide  of  potassium  preferably,  has  very  val- 
uable medicinal  properties.  It  is  regarded  as  a  specific  in 
the  reduction  of  glandular  swellings,  and  in  scrofulous  dis- 
eases. It  is  said  to  cause  the  pustules  of  small-pox  to  abort. 
In  photography,  it  is  impossible  to  estimate  its  value ;  for 
without  it,  the  art  could  not  exist  in  its  present  state. 

The  impurities  in  iodine  are  plumbago,  sulphide  of  anti- 
mony, and  iodide  of  cyanogen.  If  by  evaporation  on  apiece 
of  porcelain  there  be  any  residue,  one  or  both  of  the  former 
impurities  may  be  present;  the  latter  impurity  is  of  rare 
occurrence. 

Tests :  Free  iodine  is  easily  recognized  by  the  formation 
of  a  deep  blue  color  when  mixed  with  a  solution  of  starch  ; 
and  this  blue  color  is  volatilized  by  heat.  The  iodine  in  an 
iodide  has  first  to  be  set  free  before  it  can  be  thus  tested. 
To  effect  this,  either  a  current  of  chlorine  is  passed  through 
the  solution,  or  nitric  acid  is  added  to  it ;  by  boiling  the  solu- 
tion afterward,  the  fumes  may  be  obtained  and  thus  tested. 

Preparation  of  Hydriodic  Acid. 

Hydriodic  Acid.  —  Symbol,  I  H.    Combining  Proportion,  128yL.  Specific 

Gravity,  4.43. 

This  substance  is  a  condensable  gas  ;  at  a  temperature  of 
5 9°. 8,  it  solidifies  into  a  transparent,  colorless  mass ;  and 
water  absorbs  a  large  quantity.  The  strongest  liquid  hydri- 
odic acid  has  a  specific  gravity  of  lr7o,  when  it  boils  at  a 
temperature  between  257°  and  262°.  It  is  not  a  stable  com- 
pound ;  oxygen  from  the  air  is  absorbed,  and  iodine  is  lib- 
erated and  dissolved  by  it.  Chlorine  and  bromine  decom- 
pose it. 

Hydriodic  acid  may  be  obtained  by  several  methods. 


PREPAKATION  OF  THE  IODIDES. 


71 


From  the  property  which  iodine  possesses  of  abstracting 
hydrogen  from  several  of  its  compounds,  as  from  phosphide 
of  hydrogen,  hydrosulphuric  acid,  ammonia  and  organic 
compounds,  methods  have  been  devised  to  obtain  hydriodic 
acid  by  their  mixture.  Thus,  by  diffusing  iodine  in  powder 
through  water,  and  then  passing  a  current  of  hydrosulphuric 
acid  through  the  solution  as  long  as  iodine  is  thus  taken  up 
and  the  fluid  is  rendered  colorless.  By  this  process,  sulphur 
is  deposited  and  iodine  takes  its  place.  By  filtration,  the 
sulphur  is  removed ;  by  heat,  the  superfluous  hydrosulphuric 
acid  is  driven  away.  The  remaining  transparent  solution  is 
hydriodic  acid. 

A  solution  of  iodide  of  barium  may  be  decomposed  by  an 
equivalent  proportion  of  sulphuric  acid,  and  by  filtration  from 
the  insoluble  sulphate  of  baryta,  hydriodic  acid  is  obtained  in 
solution. 

Phosphorus  combines  very  vividly  with  iodine,  and  the 
iodide  of  phosphorus,  when  it  comes  in  contact  with  water,  is 
decomposed  into  hydriodic  acid  and  phosphoric  acid.  Liebig 
has  availed  himself  of  this  property  in  the  preparation  of  the 
iodide  of  lithium,  barium,  calcium,  potassium,  sodium,  etc. 

Lithium. — Symbol,  Li.     Combining  Proportion,  6T%. 

Barium. — Symbol,  Ba<    Combining  Proportion,  68-^.    Specific  Gravity,  4. 

Calcium. — Symbol,  Ca.   Combining  Proportion,  20. 

Potassium—  Symbol  K.  Combining  Proportion,  39. 

Sodium. — Symbol,  Na.    Combining  Proportion,  23.   Specific  Gravity,  0.97. 

Ammonium. — Symbol  NH4==Am.    Combining  Proportion,  18. 

Cadmium. — Symbol,  Cd.    Combining  Proportion,  56.    Specific  Gravity,  8.6. 

Take  one  part  of  phosphorus,  twenty-four  parts  of  iodine, 
and  forty  of  warm  water  ;  mix  them  intimately  in  a  Wedg- 
wood mortar  by  means  of  the  pestle.  The  color  of  the  fluid 
is  at  first  dark  brown,  but  becomes  transparent  as  soon  as 
the  decompositions  are  effectuated.  The  heat  of  a  water- 
bath  and  friction  will  soon  complete  the  action.  By  this 
operation,  iodine  and  phosphorus  combine,  so  as  to  form 
iodide  of  phosphorus,  which  becomes  resolved  into  hydriodic 
acid  and  phosphoric  acid  by  the  decomposition  of  the  water. 
A  little  free  iodine  added  to  the  transparent  solution  prevents 
the  formation  of  phosphorous  acid. 

Iodide  of  Barium. 

To  the  transparent  solution  above  obtained,  by  decantation 
from  any  remaining  phosphorus,  add,  in  the  first  place,  carbo- 
nate of  baryta  as  long  as  effervescence  ensues,  and  afterward 


72 


PREPARATION  OF  THE  IODIDES. 


a  little  water  of  baryta,  so  that  the  mixture  becomes  slightly 
alkaline.  By  this  decomposition  phosphate  of  baryta  is 
formed  from  the  phosphoric  acid  and  the  carbonate  of 
baryta ;  and  from  the  hydriodic  acid,  and  the  carbonate  of 
baryta,  iodide  of  barium  is  the  resulting  formation  ;  and  car- 
bonic acid  is  liberated  as  gas.  The  iodide  of  barium,  being 
soluble,  is  separated  from  the  insoluble  phosphate  by  filtra- 
tion. A  current  of  carbonic  acid  is  now  passed  through 
the  filtrate,  in  order  to  combine  with  any  remaining  solution 
of  baryta,  and  the  mixture  is  again  filtered. 

Iodide  of  Calcium. 

This  salt  is  obtained  precisely  in  the  same  way  as  the  pre- 
ceding substituting  only  milk  of  lime  for  the  barytic  salt. 
Both  these  salts  crystallize,  when  slowly  evaporated ;  they 
are,  too,  both  deliquescent.  From  either  iodide  of  barium 
or  iodide  of  calcium  the  alkaline  iodides  are  easily  formed. 

Iodide  of  Lithium. 

Add  two  ounces  of  carbonate  of  lithia  to  the  iodide  of 
either  barium  or  calcium  solutions  produced  from  seven 
ounces  of  iodine  by  the  preceding  manipulation.  The  car- 
bonate is  previously  levigated  in  water  to  an  impalpable 
consistency.  The  mixture  is  frequently  stirred  during  the 
twenty-four  hours  it  is  allowed  to  stand,  in  order  to  effect 
the  complete  precipitation  of  baryta  or  lime.  The  solution 
of  iodide  of  lithium  is  now  separated  by  filtration  from  the 
insoluble  carbonate  of  baryta  or  lime.  If  the  iodide  of  ba- 
rium or  of  lime  has  not  been  thoroughly  decomposed,  add  a 
cold  solution  of  carbonate  of  lithia  as  long  as  any  precipitate 
is  formed. 

Iodide  of  Potassium. 

Digest  a  hot  solution  of  sulphate  of  potassa  in  a  solution 
of  iodide  of  calcium  in  the  proportion  of  their  equivalents 
for  six  or  eight  hours.  Double  decomposition  ensues,  the 
sulphuric  acid  and  oxygen  of  the  potassa  combine  with  the 
lime  to  form  sulphate  of  lime,  whilst  the  iodine  and  potas- 
sium enter  into  combination  to  form  iodide  of  potassium. 
By  filtration  through  cloth  these  two  salts  are  separated. 
The  liquid,  containing  probably  still  some  iodide  of  calcium 
and  solution  of  sulphate  of  lime,  is  evaporated  and  then 
treated  with  pure  carbonate  of  potassa  as  long  as  any  pre- 
cipitate is  produced.    The  insoluble  lime  is  again  separated, 


PREPARATION  OP  THE  IODIDES. 


73 


and  the  nitrate  is  evaporated  to  crystallization.  The  mother- 
liquor  is  afterward  evaporated  to  dryness. 

Iodide  of  Sodium  and  Iodide  of  Ammonium. 

These  two  salts  may  be  prepared  in  like  manner,  either 
from  the  iodide  of  barium  or  of  calcium,  by  the  substitution 
in  one  case  of  sulphate  and  carbonate  of  soda,  and  in  the 
other  of  sulphate  and  carbonate  of  ammonia.  The  results 
are  better  with  the  iodide  of  barium,  owing  to  the  more 
perfect  insolubility  of  the  sulphate  of  baryta  after  decompo- 
sition. Both  of  these  iodides,  as  well  as  that  of  potassium, 
may  be  obtained  by  the  direct  action  of  iodine  on  the  caustic 
alkalies.  In  this  way  iodine  is  added  to  a  solution  of  potassa, 
for  instance,  until  the  latter  becomes  slightly  colored ;  the 
solution  so  obtained  contains  iodide  of  potassium  and  iodate 
of  potash  ;  it  is  evaporated  to  dryness,  and  then  heated  to 
redness,  in  order  to  convert  the  iodate  of  potash  into  iodide 
of  potassium  by  driving  off  its  oxygen.  The  fused  mass  is 
afterward  dissolved  and  crystallized.  Sulphuretted  hydro- 
gen is  sometimes  used  to  decompose  the  iodate. 

Another  method,  similar  to  the  first,  consists  in  first  ob- 
taining either  the  iodide  of  iron  or  of  zinc,  by  mixing  iodine, 
water,  and  iron-filings,  or  iodine,  water,  and  zinc-filings,  to- 
gether, and  then  heating  the  mixture  until  the  combination 
is  complete,  which  is  indicated  by  its  becoming  colorless. 
The  filtered  solution  is  next  decomposed  completely  by  add- 
ing solution  of  carbonate  of  potassa  as  long  as  any  precipi- 
tate takes  place.  The  precipitate,  which  is  either  carbonate 
of  iron  or  of  zinc,  is  removed  by  filtration  ;  and  the  filtrate 
is  evaporated  to  crystallization. 

Iodide  of  Cadmium. 

This  very  important  iodide  is  formed  precisely  in  the 
same  way  as  iodide  of  iron  or  of  zinc,  by  gently  heating  a 
mixture  of  the  filings  of  cadmium,  water,  and  iodine,  until 
the  solution  becomes  colorless. 

Impurities f  of  the  Iodides. 

The  iodides  which  are  formed  by  the  direct  contact  of  the 
two  elements  are  quite  pure  if  the  materials  are  pure ;  where- 
as, if  the  iodides  arise  from  double  decomposition,  the  com- 
bination may  sometimes  fail  in  accuracy,  in  which  case  car- 
bonates and  sulphates  of  foreign  ingredients  and  iodates  of 
the  same  base  may  be  found  in  such  iodides  ;  chlorides  may 
4 


14:  PEEP  AK  ATI  ON  OF  THE  IODIDES. 

be  present,  too,  in  the  decomposing  carbonates  and  sulphates, 
so  that  we  may  sometimes  expect  to  find  them  with  the  other 
impurities. 

Tests  of  the  Purity  of  the  Iodides. 
No  precipitate  is  produced  in  a  pure  iodide  by  solution  of 
chloride  of  barium.  If  a  precipitate  results  from  the  introduc- 
tion of  this  test,  one  or  all  of  the  following  acids  are  probably 
indicated :  carbonic,  iodic,  and  sulphuric.  Other  acids  might 
be  indicated,  but  not  probably,  because  materials  are  not  used 
in  the  preparation  of  the  iodides  containing  the  acids  hinted 
at,  as,  for  instance,  oxalic,  sulphurous,  silicic,  chromic,  hydro- 
fluoric, phosphoric,  and  boracic.  Supposing,  however,  a  pre- 
cipitate is  formed  when  the  test  is  added,  then  a  carbonate, 
iodate,  or  sulphate  may  be  one  or  all  present.  The  next  test 
is  to  find  out  which  or  how  many  of  the  three  are  present. 
Add,  therefore,  nitric  acid  to  the  precipitate  ;  if  it  becomes 
dissolved,  there  is  no  sulphate  in  the  iodide.  Carbonic  acid 
or  an  alkaline  carbonate  added  to  lime-water  produces  a 
milkiness  caused  by  the  formation  of  the  insoluble  carbonate 
of  lime  ;  and  an  iodate  in  solution  is  recognized  by  the  addi- 
tion of  chlorine-water,  or  citric,  or  tartaric  acid,  which  liber- 
ates free  iodine,  afterward  made  manifest  by  solution  of 
starch.  The  chlorides  are  tested  for  as  follows :  in  a  given 
quantity  of  the  iodide  precipitate  with  solution  of  nitrate  of 
silver,  until  nothing  more  falls  as  sediment ;  dissolve  this 
sediment  in  ammonia,  and  then  add  nitric  acid  ;  if  a  chloride 
is  present,  a  white  flocculent  precipitate  will  be  produced, 
which  is  chloride  of  silver. 


CHAPTER  XI. 


BROMINE. 

Bromine. — Symbol,  Br.   Combining  Proportion,  80.  Specific  Gravity,  2.966. 

This  peculiar  substance  was  discovered  in  1826  by  Balard, 
of  Montpellier.  It  was  originally  obtained  from  the  uncrys- 
tallizable  mother-liquor  of  sea-water,  called  bittern.  It  oc- 
curs in  sea- water  in  small  quantity  as  bromide  of  magnesium, 
or  of  an  alkali ;  but  in  much  larger  quantities  in  several 
mineral  springs,  as,  for  instance,  at  Kreuznach,  Cheltenham, 
etc.,  and  is  naturally  found  in  many  marine  plants  and  ani- 
mals. 

Preparation  of  Bromine. 

The  solution  of  the  bromides  obtained  by  evaporation  of 
sea- water,  spring-water,  or  from  the  ashes  of  certain  plants 
and  animals,  is  submitted  to  a  current  of  chlorine,  which 
takes  the  place  of  the  bromine  in  the  salts.  When  the 
liquid  ceases  to  assume  a  deeper  color  from  the  introduction 
of  chlorine,  (and  great  care  must  be  taken  not  to  add  too 
much,  because  it  combines  with  the  bromine  as  soon  as  there 
is  no  base  present  for  it  to  combine  with,)  it  is  well  shaken 
with  ether,  which,  taking  up  the  bromine,  ascends  and  swims 
on  the  surface.  This  film  is  then  decanted,  or  otherwise 
separated,  and  mixed  with  a  strong  solution  of  .potassa,  by 
which  both  bromate  and  bromide  of  potassium  are  formed  ; 
the  ether  may  now  be  removed  by  distillation,  and  the  re- 
maining solution  is  evaporated  to  dryness.  The  residual 
mass  is  then  fused,  whereby  the  bromate  of  potassa  is  con- 
verted into  bromide  of  potassium,  analogously  with  the 
iodate  or  chlorate  under  similar  circumstances.  By  distill- 
ing the  resulting  bromide  with  sulphuric  acid  and  peroxide 
of  manganese,  bromine  passes  oif  as  vapor,  and  a  sulphate  of 
the  base  remains  in  the  retort  together  with  the  manganese 
in  a  lower  state  of  oxydation. 

Bromine  thus  obtained  contains  water  and  bromide  of  car- 


76 


BROMINE. 


bon.  The  water  is  removed  by  a  second  distillation  over 
recently  fused  chloride  of  calcium.  Bromine  is  a  brownish- 
red  liquid,  which  solidifies  at — 7°T2o,  volatilizes  very  rapidly 
when  exposed  to  the  air,  and  boils  at  about  145°.  Its  smell 
is  very  disagreeable  and  pungent.  A  drop  on  the  cuticle 
destroys  it  and  produces  a  sore.  It  is  soluble  in  33T\  parts 
of  water,  and  this  solution  is  decomposed  by  exposure  to 
light  into  hydrobromic  acid. 

Test :  Chlorine  liberates  bromine  from  all  its  soluble  com- 
pounds. Ether  combines  with  it  and  collects  it ;  solution  of 
starch  produces  a  yellowish-red  color  with  it ;  it  distills  as  a 
liquid. 

Hydrobromic  Acid. 
Symbol,  BrH.  Combining  Proportion,  81.  Spec.  Grav.,  2.73. 
This  acid  is  very  analogous  in  its  formation  and  reactions 
to  hydriodic  acid.  It  can  be  prepared  by  mixing  directly 
phosphorus,  water,  and  bromine,  or  from  a  mixture  of  six 
parts  of  crystallized  sulphite  of  soda,  three  parts  of  bromine, 
and  one  of  water,  and  by  distillation.  It  can  be  obtained 
also  by  transmitting  a  current  of  hydrosulphuric  acid  through 
water,  holding  in  solution  or  suspension  a  small  quantity  of 
bromine ;  sulphur  is  deposited ;  the  hydrogen  combines  with 
the  bromine.  By  a  gentle  heat  the  fumes  of  hydrosulphuric 
acid  are  expelled  ;  and  by  filtration  the  hydrobromic  acid  is 
obtained  in  solution. 

JBromides. 

These  binary  combinations  can  be  obtained,  as  a  general 
thing,  by  manipulating  precisely  as  in  the  preparation  of  the 
iodides,  with  the  single  substitution  of  bromine  for  iodine. 
They  contain  in  like  manner,  and  for  the  same  reason,  the 
same  impurities  which  may  be  manifested  by  the  same  tests, 
with  the  exception  of  bromic  acid  instead  of  iodic;  the 
former  of  which  is  decomposed  by  chlorine. 

Preparation  of  the  Chlorides. 

Chlorine. — Symbol,  CI.    Combining  Proportion,  35.5.    Spec.  Grav.,  2.47. 

This  substance  was  discovered  in  1774  by  Scheele.  Its 
affinity  for  other  elements  is  very  great,  so  that  it  does  not 
exist  free  or  uncombined.  The  great  geological  formation 
of  rock-salt  is  a  chloride  of  sodium,  to  which  the  ocean  owes 
its  saline  taste.  It  combines  with  most  of  the  metalloids  as 
well  as  the  metals,  giving  rise  to  some  of  the  most  import- 
ant and  interesting  combinations  in  chemistry.  Chlorine, 
iodine,  bromine,  and  fluorine  form  analogous  binaries  with 


BROMINE. 


11 


hydrogen  and  the  metals ;  but  chlorine  has  greater  affinities 
for  bases  than  any  of  the  others  ;  it  is,  therefore,  employed 
in  separating  iodine  and  bromine  from  their  combinations. 

Preparation. 

Chlorine  may  be  obtained  from  any  of  its  binary  combina- 
tions by  double  decomposition.  Thus  hydrochloric  acid  is  a 
binary  consisting  of  chlorine  and  hydrogen  ;  now  by  adding 
to  hydrochloric  acid  a  material  in  which  oxygen  is  loosely 
combined,  hydrogen  and  oxygen  unite  to  form  water,  chlo- 
rine is  liberated,  and  a  chloride  of  the  base  is  at  the  same 
time  formed.  Take,  for  instance,  four  parts  of  hydrochloric 
acid,  one  part  of  the  binoxide  or  black  oxide  of  manganese, 
and  the  same  quantity  of  water.  Mix  these  ingredients  in  a 
flask  or  retort  connecting  with  a  jar  filled  with  warm  water 
and  inverted  over  the  pneumatic  trough,  or  by  a  tube  dip- 
ping to  the  bottom  of  a  large  tumbler.  By  applying  heat, 
either  from  a  lamp  or  sand-bath,  an  effervescence  is  pro- 
duced, being  the  result  of  the  decomposition  just  alluded  to. 
The  gas  as  it  passes  out  displaces  the  water  in  one  case  and 
the  air  in  the  latter. 

The  mode  by  which  it  is  procured  from  a  chloride  consists 
in  first  obtaining  from  the  chloride  hydrochloric  acid,  and 
then  proceeding  as  before.  But  the  two  operations  are  com- 
bined in  one,  that  is,  they  take  place  consentaneously  by 
mixing  all  the  materials  together  which  are  required  in  their 
separate  formations  as  follows  :  take  three  parts  of  common 
salt,  five  of  sulphuric  acid,  five  of  water,  and  four  of  binox- 
ide of  manganese,  and  apply  heat  as  before ;  the  same  re- 
sult will  ensue  as  in  the  first  case. 

Properties. 

This  substance  is  a  heavy  gas  of  a  greenish-yellow  color, 
and  exceedingly  suffocating  odor.  Under  a  pressure  of  four 
atmospheres  this  gas  is  condensed  into  a  liquid  of  a  bright 
yellow  color,  whose  specific  gravity  is  1.33.  It  is  soluble  in 
water,  which  takes  up  and  dissolves  about  two  volumes  of 
this  gas,  and  receives  the  taste,  odor,  and  other  properties 
of  the  gas.  With  very  cold  water  chlorine  enters  more 
abundantly  into  combination,  forming  a  crystalline  hydrate. 
Chlorine  in  solution,  when  exposed  to  the  light,  soon  de- 
composes the  water,  giving  rise  to  hydrochloric  acid.  Chlo- 
rine has  an  exceedingly  great  affinity  for  hydrogen,  and  re- 
moves this  latter  body  from  many  of  its  combinations,  as, 
for  example,  from  ammonia ;  still  dry  chlorine  and  hydro- 


78 


BROMINE. 


gen,  when  mixed  and  kept  in  the  dark,  do  not  combine  ;  if 
brought  into  the  full  blaze  of  the  sun,  they  combine  and  ex- 
plode ;  if  exposed  to  diffused  light,  they  combine  silently  into 
hydrochloric  acid.  Its  action  upon  metals  in  a  state  of  fine 
division  is  in  many  cases  very  energetic ;  if  a  piece  of  bronze 
or -gold-leaf  be  injected  into  a  tumblerful  of  the  moist  gas, 
the  combination  is  so  energetic  as  to  produce  flame.  The 
moist  gas  combines  with  the  hydrogen  of  organic  colors  and 
bleaches  them ;  these  colors  can  not  be  restored,  because  the 
hydrogen  can  not  be  restored  organically ;  hence  we  say  in 
such  an  instance  that  the  color  has  been  destroyed.  In  like 
manner  moist  chlorine  removes  the  hydrogen  from  putrid 
and  miasmatic  substances,  as  from  fish,  meat,  and  offensive 
localities.  It  is,  therefore,  denominated  a  disinfecting  agent. 
Its  combination  with  the  hydrate  of  lime  is  the  form  in  which 
it  is  used  both  for  bleaching  and  disinfecting. 

Chloride  of  Lime,  Chlorinetted  Lime,  etc. 

This  substance  is  prepared  by  passing  chlorine  through 
sets  of  chambers  or  compartments  of  wicker-work  containing 
layers  of  hydrate  of  lime.  The  lime  absorbs  a  large  quantity 
of  the  gas,  and  probably  combines  with  it  in  the  formation 
of  a  hypochlorite  of  lime.  Chloride  of  lime  is  soluble  to 
some  extent  in  water,  giving  to  it  an  alkaline  reaction  ;  its 
bleaching  powers  are  more  effectual  when  an  acid  is  added, 
which  liberates  the  chlorine.  This  substance  is  now  used  in 
photography  in  the  preparation  of  the  gold- toning  bath. 
When  added  to  chloride  of  gold,  which  is  slightly  acid,  it 
renders  it  alkaline,  and  at  the  same  time  chlorine  is  liberated, 
which  assists  in  producing  pure  whites  on  the  paper,  and  in 
furnishing  a  chloride  of  gold  which  is  more  effectual  in  ton- 
ing. 


CHAPTER  XII. 


NORMAL  OR  PLAIN  COLLODION,  IODIZED  COLLODION,  BROMO- 
IODIZED  COLODION. 

Normal  or  plain  collodion  is  a  solution  of  pyroxyline  in  a 
mixture  of  ether  and  alcohol,  ready  for  being  iodized  or  bro- 
mo-iodized.  This  sort  of  collodion  when  preserved  in  well 
corked  bottles  becomes  clearer  with  age,  and  the  sediment 
occupies  continually  less  space.  After  it  has  stood  for  a  week 
or  two,  the  clear  supernatant  solution  is  decanted  by  means 
of  a  syphon,  syringe,  or  stop-cock  from  the  residue  of  undis- 
solved pyroxyline  beneath,  and  again  put  aside  to  settle. 
There  is  no  fixed  rule,  arising  from  chemical  equivalents  or 
combining  proportions,  by  which  to  institute  a  fixed  formula 
for  the  preparation  of  normal  or  plain  collodion.  I  have  se- 
lected those  which  may  be  relied  upon. 

Take  of  ether,  specific  gravity,  .715  1000  parts  by  weight. 
"    "  Alcohol,  (absolute,)  .    .    .   1000  "      "  " 

In  another  vessel  shake  together  thoroughly — 

Alcohol,  (absolute,)    .    .    .  850  parts. 
Pyroxyline,  45  " 

As  soon  as  the  pyroxyline  is  completely  covered  and  satu- 
rated with  the  alcohol,  add  the  mixture  of  alcohol  and  ether, 
and  shake  well  until  the  cotton  has  completely  disappeared. 
Cork  the  vessel  carefully,  which  is  supposed  to  be  full,  and 
put  it  aside  in  a  cooly  dark  place  for  a  week  or  two,  as  before 
directed. 

If  a  glutinous  collodion,  or  a  collodion  with  more  body  be 
desired,  such  as  is  required  in  the  transfer  of  the  collodion 
film  upon  glazed  leather,  etc.,  as  much  as  fifty  parts  of  py- 
roxyline may  be  dissolved  in  the  above  proportions  of  alco- 
hol and  ether ;  on  the  contrary,  if  a  thin  collodion  be  required 
for  the  flowing  of  large  plates,  the  proportion  may  be  as  low 
as  thirty-six  or  forty  parts  of  the  prepared  cotton.  Normal 
collodion  for  present  use  may  be  filtered  ;  but  it  is  far  from 
being  as  pure  by  filtration  as  by  subsidence.    Filters  for  such 


80 


NORMAL  OK  PLAIN  COLLODION. 


purposes  may  be  procured  of  the  photographic  establish- 
ments, by  which  the  filtration  proceeds  without  the  contents 
coming  in  contact  with  the  atmosphere.  The  above  propor- 
tions are  for  the  preparation  of  what  is  denominated  alcohol 
collodion,  which  produces  a  soft,  short,  and  structureless  film 
on  the  glass  plate. 

JBromo-icliozing  Solutions  for  the  same. 


Take  of  Alcohol,  (absolute,)  100  parts. 

"    Iodide  of  sodium,  8  " 

"    Iodide  of  cadmium,  3  " 

"    Bromide  of  cadmium,  4  " 

Or, 

Take  of  Alcohol,  (absolute,)  100  parts. 

"    Iodide  of  lithium,  10  " 

"    Bromide  of  lithium,  5  " 

Or, 

Take  of  Alcohol,  (absolute,)  100  parts. 

"    Iodide  of  lithium,  6  " 

"    Iodide  of  cadmium,  6  11 

"    Bromide  of  cadmium,  2  " 

Or, 

Take  of  Alcohol,  (absolute,)  100  parts. 

"    Iodide  of  cadmium,      ....      10  " 


"    Bromide  of  ammonium,      ...      5  " 

Dissolve  the  salts  in  each  case  in  the  given  quantity  of  al- 
cohol, shaking  the  mixture  frequently,  and  preserve  it  in 
well-closed  bottles  and  in  a  dark  place. 

Collodion  for  photographic  purposes  is  prepared  from  a 
mixture  of  plain  collodion,  and  one  of  the  bromo-iodizers 
above  given,  in  the  proportion  of  ten  parts  of  the  former  to 
one  of  the  latter.  The  mixture  requires  to  be  placed  aside 
for  a  day  or  two,  before  it  arrives  at  its  maximum  sensitive- 
ness. 

Many  operators  prepare  their  collodion  directly  with  the 
requisite  quantity  of  iodizing  and  bromo-iodizing  materials, 
of  which  the  following  selection  contains  some  of  the  best 
formulae. 

Formula  of  Lieut,-  Colonel  Stuart  Worthy. 


Ether,  1  ounce. 

Alcohol,  .802,   2£  " 

Iodide  of  lithium,   15  grains. 

Bromide  of  lithium,      ....       6-J-  " 


The  pyroxyline  is  first  steeped  in  the  bromo-iodiozed  alco- 
hol, and  the  ether  then  added.    These  proportions  produce 


NORMAL  OR  PLAIN  COLLODION. 


81 


a  very  fluid  collodion,  which,  is  quite  an  advantage  in  coat- 
ing large  plates,  where  a  very  even  film  is  required.  It  is 
said  to  be  well  adapted  for  instantaneous  pictures.  The  sen- 
sitizing bath,  which  is  used  with  this  collodion,  will  be  found 
amongst  the  list  of  silver  baths  given  hereafter. 

OmmeganclvS  Formulas  for  Portraits  and  Landscapes. 
For  Portraits  of  short  exposure. 

Ether,  667  parts. 

Alcohol,   333  " 

Iodide  of  ammonium,  ....  6  " 
Iodide  of  cadmium,  ....  6  u 
Bromide  of  cadmium,  ....  3  " 
Pyroxyline,  12  " 

This  collodion  is  sure  to  be  thick  enough ;  if  too  thick, 
however,  it  can  be  rendered  more  fluid  by  the  addition  of  an 
appropriate  quantity  either  of  ether  or  absolute  alcohol.  If 
more  than  one  tenth  of  the  original  volume  be  added,  it  will 
be  necessary  to  mix  with  this  the  corresponding  quantity  of 
the  bromo-iodizers. 

For  Landscapes,  Views,  and  Direct  Transparent  Positives. 

Ether,   667  parts. 

Alcohol,   333  " 

Iodide  of  zinc,   6  " 

Iodide  of  cadmium,  ....  6  " 
Bromide  of  cadmium,     ....      3  " 

Proxy  line,   12  11 

In  this,  as  also  in  the  preceding  formula,  weigh  out  the  salts 
first ;  put  them  into  a  bottle  of  the  proper  capacity ;  add  the 
alcohol,  and  dissolve  them  by  frequent  shaking  ;  next  add  the 
ether  and  mix ;  finally  introduce  the  pyroxyline  in  small  flocks 
at  a  time,  and  shake  until  the  cotton  is  dissolved.  After  the 
solution  is  effected  the  collodion  is  put  aside  in  a  cool,  dark 
chamber,  and  allowed  to  settle  for  a  couple  of  weeks.  The 
first  collodion  will  keep  for  a  long  time ;  the  latter  is  less 
stable,  but  more  sensitive  to  certain  colors  of  foliage. 

Formulas  of  Disderi. 

NO.  I. — COLLODION  FOR  WINTER. 

First  Formula. 

Alcohol — spec.  grav.    .813,  .    4000  grains. 

Ether,         "      "       .720,     .  6000  « 

Pyroxyline,  110  " 

Iodide  of  ammonium,  ....      60  " 

Iodide  of  cadmium,      ....    40  " 

Bromide  of  ammonium,  ...       6  " 

Bromide  of  cadmium,  ....     4  u 

Iodine,   5  " 


82 


NORMAL  OR  PLAIN  COLLODION. 


Second  Formula. 

Alcohol — spec.  grav.    .813,  .     4000  grains. 

Ether,         "     "       .720,     .  6000  " 

Pyroxyline,  110  " 

Iodide  of  ammonium,      ...      50  " 

Iodide  of  potassium,     ....    50  u 

Bromide  of  ammonium,  ...      10  " 

Bromide  of  potassium,  ....    10  " 

Iodine,   5  " 

The  iodide  and  bromide  of  potassium  are  dissolved  in  the 
smallest  quantity  of  water.  A  quarter  of  the  prescribed  quan- 
tity of  alcohol  is  poured  into  a  clean  bottle ;  the  pyroxyline 
is  then  introduced,  and  the  mixture  is  well  shaken.  After 
this  operation  the  ether  is  added.  The  salts  of  iodine  and 
bromine  are  next  weighed  and  dissolved  in-  the  remaining 
quantity  of  alcohol,  and  then  mixed  with  the  solution  con- 
taining the  cotton.  The  collodion  is  put  aside  for  a  day  or 
two,  and  then  either  decanted  or  filtered. 


COLLODION  FOR  SPRING. 

Alcohol,  (as  before,)     .    .    .    5000  parts, 

Ether,  .  "   5000  " 

Pyroxyline,  100  " 

Iodide  of  ammonium, .    ...      50  " 

Iodide  of  cadmium,      ....    50  u 

Bromide  of  ammonium,  ...      10  " 

Bromide  of  cadmium,  ....    10  a 

Iodine,   5  " 


Second  Formula. 

Alcohol  and  ether,  of  each,   5000  grains. 

Pyroxyline,   100  " 

Iodine  of  ammonium  and  of  potassium,  of  each,  ...  50  " 
Bromide  of  ammonium,  and  bromide  of  potassium,  of  each,  5  " 
Iodine,   5  « 


COLLODION  FOR  SUMMER. 

Alcohol,  (as  before,)     .    .    .    4000  grains. 

Ether,  "    6000  " 

Pyroxyline,  80  " 

Iodide  of  ammonium,  ....      50  " 

Iodide  of  cadmium,     ....    30  M 

Bromide  of  ammonium,  ...       5  " 

Bromide  of  cadmium,  ....      2  " 

Iodine,   2  " 

For  copying  engravings,  etc.,  all  that  is  required  is  a  very 
simply  iodized  collodion,  without  any  bromide. 


NORMAL  OR  PLAIN  COLLODION. 


S3 


Formula  for  Copying  Collodion. 


Alcohol,  (absolute,)      .    .    .    5000  grains. 

Ether,  .720,   5000  " 

Iodide  of  cadmium,  ....  100  " 
Pyroxyline,  from  .  .  .  75  to  100  " 
Iodine,  u  2.  " 


The  collodion  film,  whether  iodized  or  bromo-iodized,  is  ren- 
dered sensitive  by  immersion  in  a  bath  of  nitrate  of  silver, 
which  will  be  described  in  the  following  pages. 

(Owing  to  the  instability  of  collodion  when  once  iodized, 
it  has  been  proposed  to  invert  the  operations,  and  to  mix  with 
the  collodion  an  equivalent  quantity  of  the  nitrate  of  silver, 
instead  of  the  iodizers  or  bromo-iodizers,  and  then  to  sensi- 
tize the  film  in  a  bath  as  follows  : 


Distilled  water,   100  parts. 

Alcohol,  25  " 

Iodide  of  ammonium,      ....    2  " 

Iodide  of  cadmium,  4  " 

Iodide  of  zinc,  2  " 

Bromide  of  zinc,   2  " 


As  soon  as  withdrawn  from  this  bath,  the  collodion  plate 
is  washed  in  distilled  water,  and  either  used  immediately  by 
immersing  it  in  a  weak  solution  of  nitrate  of  silver,  or  put 
away  to  dry.  This  process  is  due  to  Ch.  D'Orma,  and  re- 
mains to  be  tried.)  Whatever  may  be  the  difference  of  the 
composition  of  the  collodion,  arising  from  the  variety  of  for- 
mulas that  exist — for  there  is  scarcely  a  single  operator  that 
does  not  boast  of  his  own  formula — each  collodionized  plate, 
when  the  film  has  sufficiently  dried,  is  submitted  to  the  chem- 
ical influence  of  a  solution  of  nitrate  of  silver,  in  order  to  ob- 
tain by  double  decomposition  in  and  on  the  film  an  iodide, 
or  a  bromo-iodide  of  silver,  which  is  sensitive  to  the  actinic 
influence  of  light.  If  the  film  contained  a  pure  iodide,  or  a 
pure  bromo-iodide  of  silver,  without  the  presence  of  a  nitrate, 
the  results  would  not  be  satisfactory.  The  nitrates,  or  nitro- 
genized  organic  substances  seem  to  be  essential  as  accesso- 
ries in  the  photographic  operation  of  producing  collodion  posi- 
tives and  negatives.  The  most  important  salt  in  photogra- 
phic chemistry  is  nitrate  of  silver ;  it  is  the  salt  from  which 
most  of  the  other  silver  salts  are  obtained,  and  is  besides  a 
very  costly  article,  and  deserves  therefore  to  be  treated  with 
all  due  respect.  Hence  the  following  chapter  is  devoted  to 
its  service  chiefly. 


CHAPTER  XIII. 


SILVER  SALTS    OF  SILVER. 

Silver.- — Symbol,  Ag.    Combining  Proportion,  108.    Spec,  grav.,  10.474. 
Oxide  of  Silver. — Symbol,  Ag  0.    Combining  Proportion,  116. 
Chloride  of  Silver. — Symbol,  Ag.  CI.    Combining  Proportion,  143.5. 
Iodide  of  Silver. — Symbol,  Ag.  I.    Combining  Proportion,  234.36. 
Bromide  of  Silver. — Symbol,  Ag.  Br.    Combining  Proportion,  188. 
Sulphide  of  Silver. — Symbol,  Ag.  S.    Combining  Proportion,  124. 
Cyanide  of  Silver. — Symbol,  Ag.  Cy.    Combining  Proportion,  134. 
Nitrate  of  Silver. — Symbol,  Ag  0.  N05.    Combining  Proportion,  110. 
Hyposulphite  of  Silver. — Symbol,  AgO.  S2O2.    Combining  Proportion,  164. 
Sulphate  of  Silver. — Symbol,  AgO.  S03.    Combining  Proportion,  156. 
Nitrite  of  Silver. — Symbol,  AgO.  NO3.    Combining  Proportion,  154. 

Silver. 

Silver,  like  gold,  is  found  in  a  native  state ;  frequently 
too  it  occurs  as  an  alloy  containing  gold,  which  is  recog- 
nized, when  the  silver  is  dissolved  in  nitric  acid,  as  the  black 
sediment  or  oxide  of  gold.  Arsenic  and  antimony  are  found 
also  alloyed  with  it.  Several  of  the  ores  of  lead  and  copper 
contain  silver. 

As  an  ore,  the  sulphide  is  the  most  abundant ;  horn  silver, 
or  the  chloride,  occurs  native,  as  also  the  carbonate  in  small 
quantity. 

Native  silver,  and  the  silver  in  the  native  sulphide,  are 
separated  in  one  case  from  the  investing  rocky  materials, 
and  in  the  other  from  sulphur  by  a  process  called  that  of 
amalgamation.  The  ores  and  the  rocky  mass  are  reduced 
to  powder,  and  then  roasted  in  a  reverberatory  furnace  with 
about  ten  per  cent  of  chloride  of  sodium,  which  converts  the 
silver  into  chloride  of  silver.  The  pulverized  mass  is  next 
put  into  barrels,  hung  horizontally  and  capable  of  being 
rotated  by  machinery.  It  is  mixed  Avith  a  certain  quantity 
of  water,  iron  and  quicksilver.  By  being  kept  in  continual 
agitation  for  eighteen  or  twenty  hours,  the  chloride  of  silver 
becomes  decomposed  by  the  iron,  whereby  chloride  of  iron 
is  formed,  and  the  silver  set  free.  Coming  in  contact  with 
the  mercury,  an  amalgam  is  formed,  which  Hows  off  out  of 


SILVER  SALTS  OF  SILVER. 


85 


the  barrel  when  the  contents  are  made  fluid  by  the  addition 
of  water,  and  by  rotating  the  barrels  very  slowly.  The 
amalgam  is  then  subjected  to  pressure  through  chamois 
leather,  which  allows  the  mercury  to  permeate  through  its 
pores,  but  retains  the  amalgam.  By  distillation,  the  mercury 
can  be  expelled  from  the  silver  residue.  Copper  and  lead 
ores,  containing  silver,  are  treated  in  the  same  way. 

In  certain  ores  of  copper  and  lead,  silver  exists  in  small 
quantities,  and  is  melted  or  separated  by  amalgamation 
along  with  them.  If  the  quantity  is  sufficiently  great,  the 
silver  is  separated  by  a  process  called  cupellation,  which  is 
practised  in  the  mint  in  the  assay  of  metals  containing  sil- 
ver. A  cupel  is  formed  out  of  well-burnt  and  well-washed 
bone  ashes,  kneaded  into  a  thick  paste  with  water,  and 
forcibly  pressed  in  an  iron  ring.  Cupels  vary  in  size  from 
one  to  two  inches  in  diameter  or  more,  and  from  a  quarter 
of  an  inch  to  three  fourths  of  an  inch  thick,  hollowed  on  one 
side  in  the  concave  form  of  a  watch-glass.  They  are  after- 
ward dried  by  a  gentle  heat,  as  on  a  stove,  when  they  are 
ready  for  use.  The  metal,  consisting  of  copper,  silver  and 
a  large  excess  of  lead,  to  be  assayed,  or  the  silver  to  be 
purified,  is  placed  in  the  concavity  of  the  cupel,  which  rests 
on  a  muffle  in  a  furnace,  over  which  a  current  of  air  can 
flow  with  some  force.  It  soon  melts,  and  by  the  access  of 
the  draft  of  air,  the  surface  becomes  covered  with  a  film  of 
oxide;  this,  as  it  forms,  is  removed.  Lead  oxidizes  first, 
and  finally  the  copper  is  induced  to  oxidize  by  means  of  the 
oxide  of  lead,  and  forms  with  it  a  fusible  compound,  which 
sinks  into  the  pores  of  the  cupel.  As  soon  as  the  foreign 
metals  are  nearly  removed,  the  silver  assay  assumes  a  rounder 
shape,  and  when  the  last  trace  of  oxide  disappears,  there 
is  a  beautiful  play  of  prismatic  colors,  and  finally  the  silver 
button  becomes  very  brilliant,  and  exhibits  a  bright  flash  of 
light,  indicative  of  the  completion  of  the  operation. 

A  second  process  of  purifying  silver,  and  one  which  will 
be  found  better  adapted  to  the  wants  of  the  photographer, 
consists  in  dissolving  the  silver  of  commerce,  or  of  the  coin- 
age of  the  country,  in  pure  nitric  acid.  Take  one  ounce 
and  a  half  of  silver,  in  thin  laminae,  or  in  filings,  one  fluid 
ounce  of  nitric  acid,  and  two  ounces  of  pure  rain  or  distilled 
water.  Mix  the  acid  and  the  water  in  a  glazed  porcelain 
dish,  or  in  a  glass  dish  ;  then  add  the  silver,  and  place  the 
vessel  with  its  contents  in  a  sand-bath,  and  apply  a  gentle 
heat.  The  silver  will  soon  disappear  in  the  solution.  By 
this  operation,  the  nitric  acid  is  easily  broken  up  into  its  com- 


86 


SILVER  SALTS  OF  SILVER. 


binations ;  one  portion  oxidizes  the  silver  and  liberates  per- 
oxide of  nitrogen  ;  whilst  a  second  combines  with  the  oxide 
so  formed,  and  produces  the  nitrate  of  the  oxide  of  silver. 
If  the  metal  was  impure,  as  is  most  likely,  and  it  contained 
copper,  the  solution  will  be  tinged  blue  according  to  the 
quantity  of  impurity.  A  small  drop  at  the  end  of  a  glass 
stirring-rod,  will  give  rise  to  a  brilliant  blue  color,  in  a 
wine-glass  full  of  water,  made  alkaline  with  ammonia,  if 
there  be  any  copper  present ;  or  a  steel  knitting-needle, 
clipped  in  the  solution,  becomes  coated  with  a  film  of  copper, 
on  the  same  conditions. 

Supposing  the  solution,  therefore,  contains  copper,  we  may 
proceed  as  follows  to  separate  it  from  the  silver.  Add 
to  the  solution  of  the  nitrate,  a  small  quantity  of  common 
salt  dissolved  in  water,  drop  by  drop,  as  long  as  a  floccu- 
lent  precipitate  is  formed.  When  flakes  of  the  chloride  of 
silver,  thus  produced  by  double  decomposition  by  means  of 
the  chloride  of  sodium,  no  longer  appear  on  the  addition 
of  the  salt  solution,  the  precipitate  is  allowed  to  subside  in 
a  dark  room,  or  it  is  poured  directly  on  a  filter,  and  the 
fluid  containing  copper,  etc.,  is  thrown  away.  The  precipi- 
tate is  now  well  washed  by  repeatedly  filtering  pure  hot 
water  over  it,  until  a  drop  no  longer  produces  a  blue  tinge 
with  ammonia.  The  chloride  is  now  dried.  Next  weigh 
the  chloride,  and  take  twice  its  weight  of  carbonate  of 
potassa,  and  fuse  the  latter  in  a  crucible ;  when  fused,  add 
gradually  to  it  the  dry  chloride  of  silver,  which  will  be  de- 
composed, as  well  as  the  carbonate  of  potassa.  The  chloritle 
leaves  the  silver  and  gives  rise  to  chloride  of  potassium, 
whilst  the  carbonic  acid  and  oxygen  escape,  and  the  silver 
remains  diffused  through  the  mass.  By  raising  the  tem- 
perature, the  silver  sinks  into  a  button  at  the  bottom,  and 
the  fused  chloride  of  potassium  swims  on  the  surface.  The 
melted  mass  may  now  he  poured  out  into  a  pail  of  water,  or 
upon  a  hollow  stone.  The  silver  thus  obtained  and  washed, 
will  be  quite  free  from  copper,  and  all  other  metals,  except- 
ing lead  or  mercury,  which  might  be  present.  If  lead  were 
present  in  the  nitrate,  the  addition  of  sulphuric  acid  would 
produce  a  precipitate  ;  and  the  presence  of  mercury  is  easily 
shown  by  introducing  a  piece  of  polished  copper  wire  into 
a  small  quantity  of  the  nitrate  in  solution,  by  which  it  will 
be  covered  with  a  film  of  mercury  when  the  latter  is  pres- 
ent. 

Chloride  of  silver  may  be  reduced,  also,  by  fusing  it  with 


SILVER — SALTS  OF  SILVER. 


8) 


seventy  per  cent  of  chalk,  together  with  four  or  five  per 
cent  of  charcoal. 

A  third  method  of  reduction  of  the  chloride,  is  one  which 
is  very  convenient  for  those  who  do  not  possess  a  furnace, 
or  have  the  convenience  of  fusing  ores  or  residues.  Moisten 
the  chloride  with  dilute  hydrochloric  acid,  and  immerse 
a  plate  of  zinc  in  the  moistened  mass  for  several  hours. 
Decomposition  will  gradually  take  place,  the  silver  being 
deposited,  whilst  the  soluble  chloride  of  zinc  is  formed. 
After  the  chloride  has  been  thus  completely  decomposed, 
the  remaining  zinc  is  withdrawn,  and  the  precipitate  is 
washed  with  dilute  hydrochloric  acid,  until  there  is  no 
longer  any  precipitate  formed  in  the  decanted  fluid  by 
means  either  of  ammonia  or  of  sulphide  of  ammonium.  Tho 
precipitate  is  next  well  washed  with  warm  water.  It  is 
now  in  a  condition  for  being  dissolved  in  nitric  acid. 

Instead  of  precipitating  the  silver  as  chloride,  in  order  to 
separate  it  from  the  copper,  the  solution  is  evaporated  to 
dryness,  and  then  heated  nearly  to  redness.  By  this  pro- 
cess the  nitrate  of  silver  is  fused,  but  suffers  no  other  change ; 
whilst  the  nitrate  of  copper  is  decomposed,  yielding  up  per- 
oxide of  .nitrogen  and  oxygen,  and  leaving  the  insoluble 
black  oxide  of  copper  mixed  with  the  fused  silver  salt.  By 
dissolving  a  small  portion  of  the  fused  mass  from  time  to 
time  in  water,  and  testing  the  solution,  after  filtration,  with 
ammonia,  it  can  easily  be  ascertained  whether  it  be  free 
from  copper  or  not.  As  soon  as  no  copper  is  indicated,  the 
fused  mass  is  dissolved  in  pure  water  and  separated  from 
the  insoluble  residue,  evaporated  and  crystallized. 

The  oxide  of  copper  may  be  separated  from  the  nitrate 
of  copper  in  the  solution  by  substitution  of  oxide  of  silver. 
This  oxide  of  silver  is  obtained  by  precipitating  a  quantity 
of  the  given  solution  by  a  solution  of  potassa.  The  collected 
precipitates  of  oxide  of  copper  and  of  oxide  of  silver,  are  then 
well  washed,  and  afterward  boiled  with  the  remaining  parts 
of  the  impure  nitrate.  The  solution  is  then  finally  separated 
from  the  residue,  evaporated  and  crystallized. 

Finally,  the  mixed  solution  may  be  treated  with  plates 
of  copper,  whereby  the  silver  is  precipitated  in  a  state  of 
very  fine  division,  which  is  afterward  obtained  on  the  filter, 
and  thoroughly  purified  by  washing.  This  silver  is  then 
treated  with  pure  nitric  acid  until  dissolved  ;  the  solution 
is  then  evaporated  to  dryness,  redissolved,  evaporated  and 
crystallized. 

In  every  case  where  the  salt  thus  obtained  is  intended  for 


88 


SILVER — SALTS  OF  SILVER. 


photographic  purposes,  the  crystals  when  thoroughly  dried 
are  dissolved  in  pure  water,  and  again  crystallized ;  or  the 
solution  of  the  crystals  is  boiled  for  some  time  in  a  glass 
flask  containing  fragments  of  pure  silver,  or  perfectly  well- 
washed  oxide  of  silver,  (procured  as  just  indicated.)  In  this 
way  the  nitrate  of  silver,  after  evaporation  and  crystalliza- 
tion, can  be  had  in  an  absolute  neutral  condition. 

The  mother-liquor  remaining  after  the  crystals  have  been 
removed,  is  evaporated  to  dryness,  fused  and  poured  into 
cylindrical  moulds  of  the  size  of  a  quill.  In  this  form  it  is 
denominated  lunar  caustic,  and  used  principally  by  sur- 
geons for  cauterizing  erysipelatous,  ulcerated,  etc.,  surfaces. 
From  this  mode  of  its  manufacture,  it  can  not  always  be 
relied  upon  by  the  photographer  as  pure.  In  fact  it  fre- 
quently blackens  by  exposure  to  light,  whilst  pure  crystal- 
lized nitrate  of  silver,  does  not  change  by  a  similar  exposure. 
In  addition  to  impurities  of  an  organic  nature,  it  frequently 
contains,  besides,  nitrite  of  silver,  produced  by  the  decom- 
position of  the  nitrate  by  the  heat  of  fusion. 

Properties. 

Nitrate  of  silver  crystallizes  in  colorless  square  tables  ; 
it  is  an  anhydrous  salt,  and  neutral  when  carefully  prepared. 
This  salt  may  be  fused,  as  before  mentioned,  into  lunar  caus- 
tic; but  if  the  heat  be  too  great,  it  is  decomposed  into  nitrite 
of  silver,  oxygen  being  liberated ;  and  by  a  still  greater  heat 
the  nitric  acid  is  entirely  removed,  and  pure  silver  left  be- 
hind. Nitrate  of  silver  dissolves  in  one  part  of  cold  water, 
and  in  less  of  boiling  water.  It  is  soluble  also  in  about  four 
parts  of  alcohol.  The  oxide  of  the  nitrate  of  silver,  is  pre- 
cipitated by  any  of  the  alkalies  or  alkaline  earths.  In  am- 
monia, added  in  excess,  the  oxide  is  redissolved,  forming  a 
definite  compound  of  the  formula  AgO,  N05,  2NH3,  denom- 
inated ammonio-nitrate  of  silver,  which  by  evaporation  is 
obtained  in  the  crystalline  form. 

Photographic  Properties  of  the  Nitrate  of  Silver. 

Collodion  iodized  with  a  solution  of  iodide  of  silver  in 
iodide  of  potassium  does  not  produce  a  picture  when  ex- 
posed and  developed  by  the  ordinary  process  ;  nor  is  a  col- 
lodion film,  when  sensitized  in  the  bath  of  nitrate  of  silver, 
and  carefully  washed  in  the  dark-room  after  the  operation  of 
sensitizing,  any  longer  as  sensitive  to  the  actinic  influence 
as  before  ;  or  supposing  it  to  be  so,  it  no  longer  yields  a 
picture  by  ordinary  development.    It  is,  therefore,  not  the 


SILVEK — SALTS  OF  SILVER. 


89 


iodide  of  silver  alone  which  undergoes  the  actinic  impres- 
sion, but  the  iodide  in  connection  with  the  nitrate  of  silver, 
or  the  nitrate  of  the  new  baseband  probably  with  free  nitric 
acid,  which  is  easily  broken  up  or  decomposed,  and  yields 
thus  its  oxygen  to  produce  or  induce  further  decompositions. 
Whatever  the  theory  or  the  true  explanation  of  the  photo- 
graphic impression  on  the  iodides  or  bromides  may  be, 
whether  physical,  chemical,  electrical,  or  mixed,  that  is, 
physico-chemical,  etc.,  one  thing  as  yet  is  quite  certain, 
(and  this  is  certainly  the  beginning  of  knowledge,)  that  the 
rationale  of  actinism  on  any  substance  or  surface  is  a  mystery, 
has  not  been  hitherto  explained  on  unexceptional  grounds, 
is  not  satisfactorily  deduced  from  experiments.  It  is  useless 
then  to  give  a  long  dissertation  on  a  mere  hypothesis.  But 
we  do  know,  if  not  with  certainty,  at  least  nearly  so,  by 
what  conditions  the  best  results  can  be  obtained  in  refer- 
ence to  the  nitrate  of  silver  bath  in  combination  with  the 
iodized  or  bromo-iodized  collodion.  For  instance,  collodion 
containing,  amongst  other  chemical  ingredients,  free  iodine, 
indicates  at  once  that  the  silver-bath  may  be  neutral,  even 
slightly  alkaline  ;  whilst  if  the  collodion  be  new,  contain  no 
free  iodine  or  bromine,  be  colorless,  then  the  bath  appro- 
priate for  producing  a  good  picture  must  be  the  very  con- 
trary of  the  preceding,  it  must  be  slightly  acid.  We  know 
that  acids  retard  the  action  of  development,  limit  this  action 
to  the  parts  impressed  actinically,  prevent  in  consequence 
what  is  denominated  fogging.  We  know,  moreover,  from 
repeated  experiments,  that  it  is  immaterial  whether  the  col- 
lodion or  the  silver-bath  be  slightly  acid,  the  result  is  the 
same,  the  production  of  a  clear  picture  accompanied  with 
the  disadvantage  of  lengthening  the  time  of  action.  But  we 
do  not  yet  know  the  exact  conditions  of  collodion  and  bath 
by  which  clearness  and  sensitiveness  can  be  attained  in  a 
maximum  degree  in  the  shortest  time  without  exception. 

The  iodide  of  silver,  whether  produced  by  the  decomposi- 
tion of  iodide  of  cadmium,  of  lithium,  or  of  any  other  base, 
is,  in  all  probability,  equally  sensitive  ;  but  this  sensitiveness 
is  found  to  be  materially  changed  by  the  presence  of  the 
other  salt  in  the  decomposition.  From  experiments  in  this 
direction  it  is  known  that  the  greatest  degree  of  sensitive- 
ness is  arrived  at  when  the  collodion  contains  iodide  of  iron, 
and  this  probably  because  the  proto-nitrate  of  iron  is  very 
unstable  and  easily  broken  up.  With  such  an  iodizer,  how- 
ever, the  silver-bath  would  soon  be  entirely  deteriorated  by 
the  continual  introduction  of  a  developing  material ;  so  that 


90 


SILVER — SALTS  OF  SILVER. 


many  points  have  to  be  taken  into  consideration  before 
normal  conditions  can  be  isolated  or  legitimate  deductions 
drawn. 

Preparation  of  other  Salts  of  Silver. 

Other  Salts  of  Silver'. — Sulphate  of  Silver. — This  salt  is 
obtained  by  dissolving  silver  in  concentrated  sulphuric  acid 
by  the  aid  of  heat ;  or  by  double  decomposition  of  nitrate  of 
silver  with  sulphate  of  soda.  Sulphate  of  silver  is  soluble  in 
eighty-eight  times  its  weight  of  boiling  water,  from  which 
it  crystallizes  on  cooling.  Like  the  nitrate  it  is  anhydrous, 
and  forms  in  like  manner  a  distinct  and  definite  combination 
with  ammonia,  whose  equivalent  is  Ag  O.  S03  +  2  NH3  in 
fine  transparent  crystals. 

Hyposulphite  of  Silver. — This  combination  is  obtained  by 
the  double  decomposition  of  an  alkaline  hyposulphite  and 
nitrate  of  silver.  For  instance,  add  a  dilute  solution  of 
hyposulphite  of  soda  to  a  similar  one  of  nitrate  of  silver  ;  a 
white  precipitate  is  formed  which  is  soon  dissolved  in  the 
menstruum ;  after  a  while,  when  the  hyposulphite  of  soda 
has  dissolved  the  newly  formed  precipitate  to  saturation,  a 
flocculent  substance  is  formed  of  a  dull  gray  color,  which  is 
permanent.  This  second  precipitate  is  hyposulphite  of  sil- 
ver in  an  isolated  state.  But  the  hyposulphite  of  soda  con- 
tains a  large  quantity  also,  thus  giving  rise  to  a  soluble 
double  salt,  which  has  a  very  sweet  taste.  Hyposulphurous 
acid  has  a  very  powerful  affinity  for  silver,  so  that  hydro- 
chloric acid  or  a  soluble  chloride  produces  no  precipitate  in 
the  solution  of  the  double  salt  of  hyposulphite  of  silver  and 
of  soda.  In  such  a  solution,  containing  a  large  proportion 
of  waste  silver,  the  best  way  to  obtain  or  separate  the  silver 
is  to  pass  a  current  of  hydro  sulphuric  acid  through  the  solu- 
tion, in  order  that  the  silver  may  be  precipitated  as  sulphide 
of  silver.  Hyposulphite  of  silver  undergoes  spontaneous 
decomposition  into  sulphate  and  sulphide  of  silver ;  on  this 
account  the  fixing-bath  is  found  to  contain  in  general  a  large 
quantity  of  black  sediment,  which  is  sulphide  of  silver.  This 
sulphide,  when  a  sufficient  quantity  has  been  collected,  is  re- 
duced by  heat  into  sulphurous  acid  and  metallic  silver. 

Iodide  of  Silver. — This  salt  is  found  native,  and  some- 
times in  the  form  of  hexagonal  prisms.  It  may  be  formed 
artificially  by  allowing  the  vapor  of  iodine  to  play  upon 
polished  plates  of  silver,  as  in  the  Daguerreotype  process,  or 
by  double  decomposition.  When  excess  of  nitrate  of  silver 
in  solution  is  added  to  a  solution  of  iodide  of  potassium  or 


SILVER — SALTS  OF  SILVER. 


01 


to  hydriodic  acid,  a  yellow  precipitate  is  produced  ;  this  is 
iodide  of  silver ;  whereas  if  the  iodide  of  potassium  be  in 
excess,  the  precipitate  is  nearly  white,  its  soluble  and  yellow 
part  having  been  dissolved  by  the  alkaline  iodide.  The 
yellow  precipitate  is  that  form  of  the  iodide  which  is  best 
adapted  for  photographic  purposes.  It  is  insoluble  in  water 
and  in  dilute  nitric  acid  ;  almost  insoluble  in  ammonia  ;  and 
is  not  so  soon  colored  by  the  action  of  light  as  the  chloride. 
It  is  very  soluble  in  the  alkaline  iodides,  in  cyanide  of  potas- 
sium, and  hyposulphite  of  soda,  and  by  evaporation  may  be 
crystallized  out  of  them  as  double  iodides,  etc.  When  silver 
is  dissolved  in  hydriodic  acid,  crystals  of  the  iodide  of  silver 
may  be  obtained  in  the  solution  by  spontaneous  evaporation. 
Iodide  of  silver  may  be  reduced  in  the  same  way  as  the 
chloride  by  means  of  zinc.  Hydrochloric  acid  converts  it 
into  chloride  of  silver.  It  is  decomposed  by  both  chlorine 
and  bromine  which  liberate  iodine.  It  is  soluble  to  a  small 
extent  in  solution  of  nitrate  of  silver. 

Iodide  of  Silver  for  the  Silver-Bath. — Add  to  a  small 
quantity  of  iodide  of  potassium  in  solution  a  larger  quantity 
of  dissolved  nitrate  of  silver ;  allow  the  canary-yellow  colored 
precipitate  to  subside  ;  decant  the  supernatant  liquid ;  wash 
with  water  and  again  decant,  and  repeat  the  washing  several 
times.  Let  this  operation  be  performed  in  the  dark-room. 
The  yellow  precipitate,  whilst  still  moist,  is  added  to  the 
bath  of  nitrate  of  silver  in  proper  quantity  as  long  as  it  is 
dissolved  by  the  same  ;  the  solution  is  then  filtered  ;  and  as 
regards  saturation  writh  the  iodide  of  silver,  is  ready  for 
use. 

Bromide  of  Silver. — This  salt  is  found  native  in  Mexico 
and  in  Bretagne,  sometimes  in  an  amorphous  condition,  and 
sometimes  crystallized  of  a  greenish-yellow  color.  It  is 
formed  artificially  by  exposing  plates  of  silver  to  the  vapor 
of  bromine,  or  by  decomposing  nitrate  of  silver  by  an  alka- 
line, or  any  other  soluble  bromide.  The  precipitate  is  white 
at  first,  but  becomes  yellow  afterward.  It  may  be  fused,  and 
when  cool  its  color  is  intensely  yellow.  Bromide  of  silver 
is  very  sensitive  to  light,  but  the  color  when  so  acted  upon 
by  light  is  very  different  from  that  of  the  chloride.  It  is 
soluble  in  strong  ammonia  and  in  chloride  of  ammonium,  as 
also  in  hyposulphite  of  soda  and  cyanide  of  potassium.  The 
bromides  are  decomposed  by  chlorine,  whereby  bromine  is 
liberated,  and  may  be  collected  by  ether,  which,  by  agitation, 
collects  the  bromine  and  carries  it  to  the  surface,  from  which 
it  may  be  decanted. 


92 


SILVER — SALTS  OF  SILVER. 


Chloride  of  Silver. — Next  to  the  nitrate  of  silver,  the 
chloride  is  perhaps  the  most  important  combination  of  this 
metal.  It  occurs  native  as  hornrsilver  in  translucent  cubes 
or  octohedra  of  a  grayish-white  color;  its  specific  gravity 
in  the  native  form  is  5.55.  Like  the  iodide  and  bromide  of 
silver,  it  may  be  obtained  by  exposing  plates  of  silver  to  the 
vapor  of  chlorine.  The  surface  of  the  plates  soon  becomes 
covered  with  a  chalky  film,  which  is  the  chloride  in  ques- 
tion. It  is  obtained  as  an  insoluble  white  powder  by  de- 
composing nitrate  of  silver,  or  any  other  solution  of  silver 
excepting  the  hyposulphite,  by  .means  of  hydrochloric  acid 
or  a  soluble  chloride,  by  which  a  complete  interchange  takes 
place,  and  a  dense  curdy  precipitate  falls  gradually  to  the 
bottom.  After  subsidence  the  liquid  is  poured  off,  and  the 
residue  is .  well  washed  in  several  waters.  This  operation 
must  be  performed  in  the  dark-room,  because  the  chloride 
of  silver  is  very  sensitive  to  light,  and  soon  changes  from  a 
white  to  a  violet  color  in  the  sun  or  in  diffused  light.  This 
violet-colored  substance  is  a  sub-chloride  or  an  oxy-chloride, 
and  may  be  formed  directly  by  chemical  means  as  follows :  dip 
a  plate  of  polished  silver  into  a  solution  of  sesqui-chloride 
of  iron,  or  of  bichloride  of  mercury ;  the  surface  becomes 
stained  black;  the  iron  or  mercury  parting  with  a  portion  of 
its  chlorine,  is  reduced  to  a  lower  chloride,  whilst  the  silver 
film  becomes  converted  into  a  sub-chloride  of  silver.  Chlo- 
ride of  silver  is  insoluble  in  water  ;  it  is  very  soluble  in  am- 
monia, in  cyanide  of  potassium,  in  hyposulphite  of  soda,  as 
also  in  concentrated  and  boiling  solutions  of  chloride  of 
potassium,  chloride  of  sodium,  and  chloride  of  ammonium, 
from  wmich  may  be  obtained,  by  evaporation  in  one  case 
and  by  cooling  in  the  other,  crystals  of  double  salts  of  chlo- 
ride of  silver  and  the  other  substances  in  the  solvents.  Hy- 
drochloric acid  in  a  very  concentrated  state  dissolves  a 
minute  quantity  of  chloride  of  silver,  which  crystallizes  on 
evaporation  of  the  acid.  It  is  precipitated  from  all  solutions 
of  silver  salts,  as  before  mentioned,  except  from  hyposulphite 
of  silver,  by  means  of  hydrochloric  acid.  At  a  temperature 
of  500°  Fahr.  it  fuses  into  a  transparent  yellowish  fluid, 
which  when  cool  may  be  cut  with  a  knife  like  a  piece  of 
horn,  and  has  beside  some  other  resemblance  to  horn  ;  it 
hence  received  the  name  of  horn-silver  by  the  older  phar- 
maceutists. Chloride  of  silver  can  not  be  volatilized  like  the 
protochloride  of  mercury.  The  mode  of  its  reduction  into 
pure  silver  by  two  or  three  diiferent  processes  has  already 
been  given  under  the  head  of  Silver.    It  may  be  reduced 


SILVER — SALTS  OF  SILVER. 


93 


also  by  a  mixture  of  carbonate  of  potassa,  cane-sugar,  or 
starch-sugar  and  water. 

Tests  :  Chloride  of  silver  is  distinguished  from  all  other 
precipitates,  having  the  same  color,  by  the  property  which 
it  possesses,  when  exposed  on  a  white  saucer  or  evaporat- 
ing-dish,  of  becoming  changed  into  a  violet-colored  sub- 
stance. Its  insolubility  in  nitric  acid,  and  solubility  in  am- 
monia, is  also  an  excellent  test  when  combined  with  the 
preceding. 

Photographic  Properties  of  Chloride  of  Silver. 

There  is  quite  an  analogy  in  the  application  of  iodide  of 
silver  and  chloride  of  silver ;  the  former  being  essentially  in 
combination  with  a  nitrate  or  free  nitric  acid,  the  sensitive 
collodion  film ;  whilst  the  latter,  in  combination  likewise 
with  a  nitrate  or  free  nitric  acid,  forms  the  sensitive  film 
on  gelatine,  albumen,  arrow-root,  resinized,  gutta-percha,  or 
plain  paper.  These  papers  have  first  imbibed,  or  have  been 
invested  with,  certain  soluble  chlorides,  as  of  ammonium, 
sodium,  etc.,  by  floating  or  otherwise,  and  then  dried.  By 
double  decomposition  afterward  these  chlorides  are  con- 
verted, by  floating  the  papers  on  a  solution  of  nitrate  of 
silver,  into  chloride  of  silver.  Organic  salts  of  silver  are 
formed  simultaneously,  such  as  the  albuminate,  etc.,  which 
assist  in,  or  detract  from,  the  photographic  operation.  Of 
this  I  shall  speak  more  extensively  when  I  have  to  discuss 
the  theory  and  practice  of  Positive-printing  on  paper. 

Other  Uses  of  Chloride  of  Silver.  —  The  solution  used 
in  galvano-plasty,  or  electrolysis,  for  plating  with  silver  is 
made  by  dissolving  in  a  saturated  solution  of  cyanide  of 
potassium  the  moist  and  undecomposed  chloride  of  silver  to 
saturation,  and  then  diluting  this  solution  by  four  or  five 
times  its  bulk  of  water. 

The  grayish-colored  powder  used  for  dry-plating  or  for 
silvering  dial-plates,  thermometer-scales,  etc.,  consists  of 
one  part  of  chloride  of  silver,  five  parts  of  cream  of  tartar, 
and  four  of  common  salt,  rubbed  on  with  a  piece  of  flannel 
or  sponge  dipped  in  solution  of  salt. 


CHAPTER  XIV. 


REDUCING  AGENTS — DEVELOPERS. 

As  already  remarked  in  a  preceding  chapter,  the  actinic  im- 
pression of  an  object  on  the  prepared  collodion  film  is  invisible 
or  latent ;  it  is  like  the  impression  of  the  finger  on  a  plate  of 
copper,  or  of  a  warm  piece  of  metal  on  a  glass  mirror;  after 
the  removal  of  the  finger,  or  of  the  metal,  the  eye  can  not 
distinguish  the  spot  where  the  impression  was  made  ;  but,  as 
Moeser  first  illustrated,  breathing  upon  the  glass  will  make 
the  impression  manifest,  will  show  that  the  image  was  there 
in  a  latent  or  invisible  condition.  In  like  manner  a  plate  of 
polished  silver  may  be  substituted  for  the  glass  mirror,  and 
excised  metallic  figures  be  placed  when  warm  on  its  sur- 
face ;  the  impression  is  quite  invisible,  but  becomes  visible 
when  the  silver  plate  is  exposed  to  the  vapor  of  mercury. 

Furthermore,  if  the  glass  mirror,  or  the  polished  metallic 
plate  be  exj>osed  in  the  camera  before  an  object,  and  the  for- 
mer be  breathed  upon,  and  the  latter  exposed  to  the  vapor 
of  mercury,  in  either  case  the  picture  becomes  visible  ;  but 
the  picture  in  either  case  is  a  mere  breath,  an  evanescent 
shadow.  It  gives  us,  however,  a  distinct  idea  of  what  is 
meant  by  a  developer,  it  is  the  prototype  of  a  reducing  agent. 
In  chemistry  is  understood  by  a  reducing  agent,  a  substance, 
which,  when  applied  to  a  combination,  properly  speaking  of 
a  metal,  will  decompose  the  compound  in  such  a  way  as  to 
leave  the  metal  in  the  reguline  condition,  isolated  from  the 
other  combining  materials.  Hydrogen  and  carbon  are  the 
best  chemical  reducing  agents.  Pass  a  current  of  hydrogen 
through  a  glass  tube  containing  oxide  of  copper  heated  to 
redness  ;  in  this  state  the  hydrogen  has  more  affinity  for  the 
oxygen  of  the  oxide  than  the  copper  possesses ;  the  two  me- 
talloids therefore  pair  and  pass  off  in  combination  as  the  va- 
por of  water,  leaving  the  copper  reduced  to  the  metallic  state. 
A  solution  of  nitrate  of  silver,  impressed  by  blocks  upon  silk, 
is  reduced  to  a  bright  film  of  silver  when  exposed  to  hy- 
drogen gas.    Heat  a  mixture  of  charcoal  and  oxide  of  lead 


REDUCING  AGENTS — DEVELOPERS. 


95 


in  a  crucible,  carbonic  acid  results  from  the  combination  of 
charcoal  and  oxygen,  whilst  the  metal  lead  is  reduced.  Elec- 
tricity, Heat  and  Light  are  all  reducing  agents.  Fill  a  tum- 
bler with  the  solution  of  chloride  of  silver  in  cyanide  of  potas- 
sium, just  above  mentioned.  Next  take  two  copper  wires, 
to  the  end  of  one  solder  a  quarter  of  a  dollar,  to  the  other 
attach  *on  a  hook  any  clean  and  well-polished  article  of  brass 
or  copper  ;  the  other  end  of  the  latter  wire  is  now  fastened 
to  the  negative  or  zinc  side  of  a  galvanic  battery,  whilst  the 
end  of  the  other  copper  wire  is  fixed  on  the  positive  or  pla- 
tinum side  of  the  battery.  Insert  the  piece  of  silver  and  the 
brass,  etc.,  object  in  the  tumbler,  but  not  in  contact ;  the  sil- 
ver in  the  solution  will  immediately  begin  to  be  reduced,  and 
by  the  electrical  current,  will  be  carried  to  the  negative  side 
and  deposited  on  the  object  to  be  plated. 

By  heat  alone  several  of  the  oxides  are  reduced  to  the  me- 
tallic state,  as  for  instance,  oxide  of  mercury,  of  silver,  etc. 
Some  are  reduced  by  light,  as  those  of  gold. 

Many  of  the  salts  of  the  metals  are  reduced  by  the  supe- 
rior affinity  of  other  metals.  Immerse  a  piece  of  copper  wire 
in  a  solution  of  nitrate  of  mercury ;  nitrate  of  copper  will  be 
formed  and  mercury  precipitated  on  the  copper.  Mercury 
precipitates  silver  from  nitrate  of  silver ;  zinc  precipitates 
lead  from  the  acetate  of  this  metal,  and  iron  precipitates  cop- 
per from  its  nitrate. 

Potassium  and  sodium  by  their  very  superior  attraction 
for  oxygen  are  regarded  as  among  the  best  reducing  agents  ; 
cyanide  of  potassium  unites  the  properties  of  carbon  and  po- 
tassium in  the  way  of  reduction.  The  protosalts  of  iron  are 
easily  changed  into  the  persalts  when  brought  into  contact 
with  oxides  in  which  the  oxygen  has  been  loosened  in  its  af- 
finities, or  when  in  contact  with  chlorine  or  nitric  acid ;  and 
the  metallic  base  is  precipitated.  Tannic  acid,  gallic  acid, 
pyrogallic  acid  and  formic  acid  are  all  excellent  reducers. 
The  last  substances  enumerated  are  those  in  general  use  as 
reducers  or  developers  in  photography  ;  but  the  substance  re- 
duced or  precipitated  by  them  is  not  always  a  pure  metal ; 
in  some  instances  it  appears  pure  and  metallic,  in  others  black 
and  free  from  metallic  lustre,  as  if  it  were  mixed  with  organic 
material.  The  act  of  reduction  in  photography  consists  in 
reducing  a  silver  compound ;  this  reduction  is  aided  by  the 
presence  of  nitric  acid  or  a  nitrate  ;  without  nitric  acid  or 
a  nitrate  the  development  in  question  seems  impossible,  and 
it  is  equally  impossible  without  the  previous  action  of  light. 
Now  let  us  see  what  the  action  of  the  protosulphate  of  iron 


96 


REDUCING  AGENTS — DEVELOPERS. 


is  upon  the*  oxide  of  silver  in  solution,  as  also  of  nitric  acid 
upon  the  protosulphate  of  iron.  In  the  first  place  dissolve  a 
crystal  of  green  vitriol  in  a  drop  or  two  of  nitric  acid  :  decom- 
position ensues  ;  the  nitric  acid  is  broken  up  into  parts,  fumes 
of  the  peroxide  of  nitrogen  are  liberated,  and  a  reddish  col- 
lored  persulphate  of  iron  is  produced  from  the  absorption  of 
oxygen.  Secondly,  dissolve  a  small  quantity  of  the  oxide  of 
silver  in  nitrate  of  ammonia,  and  add  solution  of  the  proto- 
sulphate of  iron  to  the  ammonio -nitrate.  The  mixed  solution 
becomes  colored  and  turbid,  and  a  deposit  subsides,  which 
is  found  to  be  pure  silver. 

By  experience  we  know  that  the  film  on  a  collodion  plate, 
after  development  with  protosulphate  of  iron,  is  also  pure  sil- 
ver, soluble  in  nitric  acid.  Now  coupling  the  two  facts  together 
that  both  light  and  nitric  acid  are  required  before  the  reduc- 
tion can  take  place,  and  also  that  there  must  be  present  the 
oxide  of  silver  in  solution,  (for  the  reduction  is  ineffectual 
with  the  iodide  of  silver,)  it  seems  as  if  we  were  indicated  to 
believe  that  the  action  of  light  produced  an  oxide  in  all  those 
parts  where  it  struck,  or  loosened  the  oxide  of  the  nitrate  of 
silver  present  on  the  film,  wherever  the  actinic  rays  made  an 
impression.  This  loosening  of  the  oxide  of  silver  from  its 
connection  with  the  acid  may  be  effectuated  by  the  conjoint 
action  of  light  and  iodine  or  bromine,  whereby  a  double  de- 
composition is  instituted  the  very  reverse  of  that  which  or- 
dinarily takes  place,  that  is,  iodide  of  silver  and  nitrate  of 
potassa  are  reconverted  by  light  into  iodide  of  potassium  and 
nitrate  of  the  oxide  of  silver  in  the  act  of  formation,  or  prop- 
erly speaking,  into  nitric  acid  and  oxide  of  silver,  held  in 
abeyance  by  some  power  (light  or  electricity)  which  pre- 
vents their  union.  If  this  were  so,  it  seems  to  me,  w^e  have 
an  assemblage  of  materials  in  the  right  condition  for  pro- 
ducing the  effects  which  in  reality  take  place.  With  such 
circumstances  and  conditions  it  is  easy  to  see  how  a  solution 
of  protosulphate  of  iron  would  reduce  the  oxide  of  silver  into 
a  film  of  pure  silver,  whose  thickness  would  vary  as  the  in- 
tensity of  the  actino -chemical  action.  There  is  no  absurdity 
in  supposing  the  possibility  of  the  inversion  alluded  to.  The 
vapor  of  water,  by  passing  through  an  iron  or  porcelain  tube 
heated  to  a  white  heat,  is  decomposed  into  its  elements ; 
whereas  if  the  heat  of  flame  be  applied  to  a  mixture  of  these 
gases,  they  recombine  instantaneously  and  reproduce  the 
vapor  of  water.  Other  analogous  inversions  of  chemical  af- 
finity are  known  to  the  chemist. 


REDUCING  AGENTS — DEVELOPERS. 


97 


Iron  Developer. 

Iron. — Symbol,  Fe.  Combining  Proportion,  28.  Spec.  Grav.,  7.8. 

Protoxide  of  Iron.— Symbol,  FeO.       "  "  36. 

Sesquioxide  of  Iron.— I Symbol,  Fe2  03.  "  "  80. 

With  iron,  as  with  some  metals,  we  have  two  classes  oi 
salts,  the  protosalts  and  the  persalts,  that  is,  the  salts  of  the 
protoxide  and  the  salts  of  the  peroxide.  The  two  classes 
are  not  equally  permanent,  sometimes  the  protosalts  being 
the  stable  salts,  and  sometimes  the  other.  Those  salts  which 
are  not  stable  are  liable  to  part  with  their  oxygen,  or  to  take 
Tip  more  oxygen,  according  to  their  condition  of  stability. 
Thus  it  happens  with  the  iron  compounds.  The  protoni- 
trate,  for  instance,  is  changed  by  boiling  into  a  salt  of  the 
sesquioxide  ;  and  the  proto-sulphate  is  apt  to  undergo  decom- 
position and  assume  a  coppery  appearance,  by  changing  into 
the  persalt.  This  property  in  salts  and  acids  of  communicat- 
ing to,  or  of  abstracting  oxygen  from  other  chemical  substances 
in  contact  with  them  is  made  available  in  various  reactions ; 
as,  for  instance,  in  toxicological  investigations,  arsenic  acid  is 
reduced  by  sulphurous  acid  into  arsenious  acid  ;  on  this  ac- 
count sulphurous  acid  is  properly  called  a  reducing  agent. 
In  photography,  as  already  remarked,  the  sulphate  of  the 
protoxide  of  iron  passes  easily  into  the  sesquisalt,  by  ab- 
stracting oxygen  from  somewhere,  whereby  a  picture  on  the 
collodion  film  becomes  visible. 

Nitrate  of  the  Protoxide  of  Iron. 

Symbol,  FeO,  N  05. 

This  substance  is  obtained  best  by  decomposing  the  sul- 
phate by  means  of  nitrate  of  baryta.  The  solution  has  a  green 
color,  like  all  the  protosalts ;  it  can  not  easily  be  crystallized, 
because  a  high  temperature  decomposes  it  into  a  sesquisalt. 

Sulphate  of  the  Protoxide  of  Iron. 
Symbol,  Fe  0,  S  O3,  H  0  +  6  Aq.    Combining  Proportion,  139. 

Sulphate  of  iron  is  obtained  by  dissolving  iron  to  satura- 
tion in  a  dilute  solution  of  sulphuric  acid,  decanting  the  su- 
pernatant liquid,  evaporating  and  setting  aside  for  crystalliza- 
tion. These  crystals  have  a  slightly  bluish-green  color.  When 
exposed  to  the  air  the  crystals  become  colored  of  a  brick- 
red  color,  by  decomposition ;  and  if  the  crystals  be  exposed 
to  a  temperature  of  212°  Fahr.,  or  a  little  upwards,  they  part 
with  the  six  equivalents  of  the  water  of  crystallization,  and 
5 


98 


REDUCING  AGENTS 


• — DEVELOPERS. 


crumble  into  a  grayish-white  powder  ;  at  a  higher  tempera- 
ture the  remaining  equivalent  of  water  may  be  expelled.  It 
is  from  the  anhydrous  salt  now  left  that  anhydrous  sulphu- 
ric acid  is  obtained,  or  at  least  the  very  strong  and  fuming 
sulphuric  acid  of  Nordhausen.  In  the  preparation  of  this 
acid  from  the  residual  salt  above  mentioned,  a  high  temper- 
ature is  required,  by  which  the  affinity  of  the  acid  for  the 
base  is  destroyed,  and  is  expelled,  leaving  in  the  retort  a 
pulverulent  red  mass,  the  colcothar  of  the  alchemists,  or  ses- 
quioxide  of  iron.  Sulphate  of  iron  is  soluble  in  two  parts  of 
cold  water  and  three  fourths  of  a  part  of  boiling  water ;  the 
solution  is  neutral.  This  salt  is  not  soluble  in  alcohol ;  if  al- 
cohol be  added  to  a  solution  of  sulphate  of  iron,  the  salt  is 
precipitated  in  a  white  granular  form,  which  is  very  conve- 
nient for  photographic  purposes  ;  by  this  process  it  is  purified 
from  any  superfluous  acid  which  it  may  contain. 

Double  Sulphate  of  Iron  and  Ammonia. 

It  has  been  proposed  by  Meynier  to  substitute  this  double 
salt  for  the  protosulphate  of  iron,  because  of  its  permanency 
when  exposed  to  the  air,  or  its  less  liability  to  decomposi- 
tion.   This  double  salt  was  described  by  Mitscherlich. 

Reparation. 

Take  equivalent  proportions  of  sulphate  of  iron  and  sul- 
phate of  ammonia,  that  is,  139  parts  of  the  former  to  75  of 
the  latter,  and  dissolve  the  salts  in  four  or  five  parts  of  water  ; 
when  the  solution  is  complete,  filter  and  evaporate,  and  af- 
terward set  aside  to  crystallize.  The  solution  for  photo- 
graphic purposes  can  be  prepared  in  quantity,  and  it  keeps 
well  without  undergoing  much  change.  The  formula  for 
development  with  this  double  salt  does  not  differ  from  the 
simple  protosulphate ;  it  contains  alcohol,  water,  and  acetic 
acid. 

Sulphide  of  Iron. 

Symbol,  Fe  S.    Combining  Proportion,  44. 

This  substance  is  not  used  directly  in  any  photographic  ope- 
ration ;  but  for  the  chemist  and  experimental  photographer 
it  has  great  value,  because  it  assists  in  the  formation  of  hy- 
drosulphuric  acid,  which  is  by  far  the  most  valuable  reagent 
in  chemistry. 

Preparation. 

Heat  a  bar  of  iron  in  a  blacksmith's  forge  to  a  welding 
heat,  and  then  rub  it  on  a  stick  of  sulphur ;  combination  will 


REDUCING  AGENTS — DEVELOPERS. 


99 


take  place  very  vividly,  and  the  new  compound  will  drop  off 
like  melted  wax.  When  cool  it  has  a  dark  gray  color  and 
metallic  appearance.  Pulverized  and  thrown  into  dilute 
sulphuric  acid,  it  gives  rise  to  hydro-sulphuric  acid,  which 
may  be  collected  or  used  immediately  by  passing  it  through 
a  given  fluid,  as  for  instance,  an  old  hyposulphite  bath,  in 
order  to  reduce  the  silver  in  the  form  of  the  sulphide  of  silver. 

Tannic  Acid —  Gallic  Acid — Pyrogallic  Acid, 

The  first  substance  exists  in  the  vegetable  kingdom,  and 
is  obtained  from  the  astringent  materials  in  various  plants, 
but  especially  from  oak  bark  and  nutgalls,  which  are  ex- 
crescences on  the  leaves  of  an  oak  (quercus  infectoria)  pro- 
duced by  an  insect.  The  second  does  not  exist  naturally, 
or  at  least  in  very  minute  quantity,  but  is  rather  a  produc- 
tion arising  from  tannic  acid  when  exposed  to  moisture  and 
the  atmosphere  ;  and  the  third  is  obtained  from  the  second 
by  sublimation  at  a  given  temperature.  The  peculiar  prop- 
erty of  the  astringent  principle  in  various  barks,  is  to  occa- 
sion a  precipitate  in  solutions  of  gelatine,  and  in  several  me- 
tallic salts.  It  produces  in  solutions  of  the  persalts  of  iron  a 
dark  blue  or  dingy  green  color,  according  to  the  bark  from 
which  it  is  extracted.  From  the  property  of  acting  upon 
gelatine,  by  which  skins  are  converted  into  leather,  it  is  de- 
nominated tannin;  and  from  its  power  of  combining  with 
metallic  bases,  and  forming  precipitates,  etc.,  it  is  regarded 
as  an  acid,  and  termed  tannic  acid. 

The  tannin  extracted  from  the  wood,  the  bark,  the  leaves 
and  the  galls  of  oak,  the  twigs  of  the  black  currant  and  of 
the  sumac,  the  petals  of  the  pomegranate,  etc.,  and  from  the 
roots  of  several  plants,  produces  in  solutions  of  the  sesqui- 
salts  of  iron,  a  deep  blue  color,  the  foundation  of  writing-ink. 

Whereas  the  tannin  from  horse-chestnuts,  the  different 
varieties  of  tea,  from  catechu  and  kino,  cinchona  bark,  cin- 
namon, cassia,  etc.,  yields  a  green  precipitate  with  solutions 
of  the  persalts  of  iron. 

Tannic  Acid. — Symbol,  C54H22O34. 
Gallic  Acid. — Symbol,  CHH6Oio. 
Pyrogallic  Acid. — Symbol,  C6H303. 

Preparation  of  Tannic  Acid. 

Tannic  acid  is  prepared  by  a  process  suggested  by  Pelouze. 
Take  an  elongated  glass  funnel,  terminating  at  the  upper 
orifice  like  a  bottle,  which  can  be  closed  by  a  cork.  The 
lower  orifice  is  loosely  closed  by  a  plug  of  cotton-wool,  or  a 


100 


REDUCING  AGENTS — DEVELOPERS. 


piece  of  sponge ;  the  body  of  the  funnel  is  then  half  filled 
with  powdered  nutgalls,  over  which  is  poured  a  quantity  of 
commercial  ether,  so  as  to  fill  the  remaining  part  of  the  fun- 
nel. The  cork  is  then  replaced  loosely,  admitting  a  little  air 
as  the  filtration  proceeds.  The  liquid  that  passes  through 
the  funnel,  and  accumulates  beneath,  forms  two  layers  ;  the 
upper  one  light  and  very  fluid,  and  the  lower  heavier  and 
of  a  yellowish  tinge*.  Ether  is  added  above  the  galls,  from 
time  to  time,  until  the  lower  stratum  of  the  filtrate  no  longer 
increases  in  depth.  The  funnel  is  then  removed  from  the  ves- 
sel beneath,  and  the  lower  stratum  is  separated  by  means  of 
a  glass  syringe  inserted  to  the  bottom ;  or  the  whole  con- 
tents can  be  placed  in  a  funnel,  of  which  the  lower  aperture 
is  closed  by  the  finger.  In  this  way  the  dense  fluid  is 
allowed  to  flow  off,  and  when  the  whole  has  been  thus  re- 
moved, the  aperture  is  again  closed  with  the  finger,  and  the 
light  fluid  is  poured  into  a  retort,  and  distilled  at  a  gentle 
heat.  It  consists  principally  of  ether.  The  dense  fluid  is 
then  washed  with  concentrated  ether,  from  which  it  is  sep- 
arated as  before,  and  afterward  evaporated  at  a  low  tem- 
perature to  dryness.  The  resulting  substance  is  light  and 
spongy,  of  an  ochreous  color.  It  is  pure  tannin  or  tannic 
acid,  in  quantity  about  thirty-five  per  cent  of  the  galls  em- 
ployed. It  has  a  slightly  acid  reaction,  is  very  astringent, 
not  bitter.  It  is  soluble  in  water  and  alcohol,  but  sparingly 
soluble  in  ether.  With  mineral  acids,  albumen,  gelatine, 
salts  of  the  alkaloids,  mineral  bases,  it  forms  precipitates. 
Salts  of  the  protoxide  of  iron  are  not  changed  by  tanni-c 
acid ;  but  those  of  the  sesquioxide  give  a  deep  bluish-black 
precipitate. 

Tannic  acid  is  used  extensively  in  photography  in  the 
preparation  of  the  dry  plates  by  the  Tannin  Process  of  Ma- 
jor Russell.  This  process  is  fully  described  in  a  subsequent 
chapter. 

Preparation  of  Gallic  Acid. 

As  before  observed,  gallic  acid  exists  in  minute  quantity 
in  nutgalls ;  but  it  is  rather  a  product  of  the  decomposition 
of  tannin,  than  a  naturally  existing  substance.  Mix  pow- 
dered nutgalls  into  a  thin  paste,  and  expose  it  to  the  air  for 
two  or  three  months,  taking  care  to  replace  the  water  as  it 
evaporates.  The  mass  becomes  mouldy,  and  darker  in  color 
by  this  exposure ;  it  is  then  pressed  in  a  cloth ;  afterward, 
the  residue  is  boiled  in  water  and  filtered  whilst  hot.  On 
cooling,  crystals  of  gallic  acid  are  deposited,  which  are  puri- 


REDUCING  AGENTS  DEVELOPERS. 


101 


fied  by  boiling  in  eight  parts  of  water  and  one  fifth  of  their 
weight  of  animal  charcoal.  After  filtration  and  cooling,  pure 
crystals  of  gallic  acid  are  deposited,  in  the  form  of  long- 
silky  needles.  During  exposure  to  the  atmosphere,  moist 
tannic  acid  absorbs  oxygen,  and  liberates  carbonic  acid,  so 
that  gallic  acid  is  altogether  a  definite  and  distinct  com- 
pound. When  quite  purified,  it  has  no  effect  upon  a  solu- 
tion of  gelatine ;  it  has  an  acid  and  astringent  taste.  The 
solution  is  soon  decomposed.  Gallic  acid  is  soluble  in  one 
hundred  parts  of  cold  water,  and  in  three  of  boiling  water. 
It  has  no  effect  upon  the  solution  of  salts  of  the  protox- 
ide of  iron,  but  upon  those  of  the  sesquioxide,  it  produces 
a  deep  bluish-black  precipitate,  which  disappears  when  the 
liquid  is  heated,  the  sesquioxide  being  converted  into  the 
protoxide  by  the  decomposition  of  the  gallic  acid.  Gallic 
acid  meets  with  an  extensive  application  in  photography,  in 
various  processes,  as  in  the  Tannin  Process  of  Major  Russell, 
the  Dry  Process  of  Taupenot,  etc.,  and  in  the  process  of  Posi- 
tive Printing  by  Development. 

Preparation  of  Pyrogallic  Acid. 

The  etymology  of  the  word  indicates  the  origin  of  this 
substance.  When  gallic  acid  is  heated  to  the  temperature 
of  410°  Fahrenheit,  and  kept  at  this  temperature,  in  an  oil- 
bath,  a  volatile  substance  sublimes  of  a  beautiful  white  color, 
in  crystalline  plates.  This  is  pyrogallic  acid,  which  is  sol- 
uble in  water,  alcohol,  and  ether.  The  solution  of  pyrogallic 
acid  soon  turns  brown  when  exposed  to  the  air,  by  becom- 
ing oxidized.  It  communicates  a  blackish-blue  color  to  the 
solutions  of  the  salts  of  the  protoxide  of  iron,  and  reduces 
those  of  the  sesquioxide  to  the  state  of  the  protoxide.  When 
mixed  with  an  alkaline  solution,  it  absorbs  a  large  quantity 
of  oxygen  from  the  atmosphere,  and  has  been  used  in  the 
analysis  of  air  for  this  special  purpose.  When  gallic  acid  is 
raised  to  a  higher  temperature  than  410°  Fahrenheit,  that  is, 
to  480°  Fahrenheit,  it  is  decomposed  into  carbonic  acid, 
water,  and  a  new  substance  denominated  metagallic  acid, 
being  the  black  shining  residue  left  in  the  retort.  Pyrogal- 
lic acid,  at  the  proper  temperature,  is  in  like  manner  decom- 
posed into  metagallic  acid  and  water. 

Owing  to  the  property  possessed  by  pyrogallic  acid  of  ab- 
sorbing oxygen  from  bodies  with  which  it  is  in  contact,  it  is 
as  yet  the  second  best  developer  of  the  latent  image  in  the 
collodion  process ;  and  taking  into  consideration  the  nature 
of  the  image  produced,  where  the  time  of  exposure  is  not 


102 


REDUCING  AGENTS  DEVELOPERS. 


important,  it  certainly  is  the  most  easy  and  reliable  devel- 
oper. There  is  no  doubt  that  a  solution  of  protosulphate  of 
iron  acts  more  quickly ;  or,  what  is  meant,  requires  a  much 
shorter  time  of  exposure.  From  the  experiments  in  ordi- 
nary landscape  photography,  I  have  frequently  observed  a 
difference  of  three  to  one  in  the  time  in  favor  of  the  sul- 
phate of  the  protoxide  of  iron. 

Acids  in  Developing  Solutions, 

The  solution  of  protosulphate  of  iron,  or  of  pyrogallic 
acid,  is  frequently  much  more  energetic  in  reduction  than  is 
manageable,  and  proceeds,  after  the  image  has  been  thor- 
oughly developed,  to  act  upon  those  parts  on  which  the 
actinic  influence  has  been  but  very  feeble  or  almost  imper- 
ceptible. The  difficulty  in  such  a  case  is  two-fold.  It  con- 
sists in  flowing  the  plate  uniformly  and  instantaneously; 
otherwise  lines  of  demarkation  will  be  quite  visible  at  those 
edges  where  the  fluid  was  momentarily  retarded ;  and  sec- 
ondly, in  stopping  the  progress  of  development  uniformly 
and  instantaneously.  Many  excellent  negatives  have  been 
ruined  by  the  misfortunes  arising  from  the  difficulties  alluded 
to ;  and  yet  Instantaneous  Photography  has  to  search  in  this 
direction  for  the  surest  means  of  success,  rather  than  upon 
any  fortuitous  advantages  in  the  collodion.  The  operation  of 
light  is,  practically  speaking,  instantaneous,  because  its  ve- 
locity is  greater  than  conception.  A  certain  time  always 
elapses  between  the  opening  and  closing  of  the  shutter,  be- 
fore the  lenses,  in  the  operation  of  instantaneity ;  and  in  this 
time  light  has  traveled  thousands  of  miles,  or  rushed  with  its 
thousands  of  miles'  momentum  on  the  sensitized  plate.  The 
picture,  therefore,  is  already  there;  because  the  impression 
has  been  made.  It  remains,  consequently,  to  find  a  reduc- 
ing agent  so  refined  and  energetic  as  to  effectuate  the  proper 
reduction.  With  the  ordinary  quantity  of  acids  in  our  de- 
velopers, we  can  scarcely  hope  for  success ;  but  with  their 
diminution,  and  a  proportionate  increase  of  velocity  in  the 
manipulation  of  flowing  the  plates,  and  of  stopping  the  fur- 
ther advance  of  reduction,  instantaneous  photography  has,  in 
my  opinion,  to  seek  a  clue  for  its  reliable  performance.  As 
a  general  rule  in  practice,  the  photographer  requires  less  acid 
in  the  developer  according  as  the  time  of  exposure  is  less  ; 
consequently,  the  positive  on  glass,  or  prepared  iron  plate, 
called  the  ambrotype  and  the  melainotype,  requires  a  much 
less  acid  developer  than  the  negative,  where  the  time  of  ex- 
posure is  much  longer.    In  like  manner,  two  photographers 


REDUCING  AGENTS — DEVELOPERS. 


103 


may  be  in  the  habit  of  operating,  the  one  with  short  expo- 
sures, and  the  other  with  long  exposures;  but  it  will  be 
found  that  the  developer  of  the  former  is  much  less  acid 
than  that  of  the  latter.  Now  it  may  be  asked  :  What  is  the 
reason  that  the  same  developer  can  not  be  used  for  the  two 
kinds  of  pictures  ?  Because,  in  the  case  of  ambrotypes,  if 
the  developer  be  acid  as  is  the  case  for  negatives,  the  reduc- 
tion will  be  very  slow,  and  most  likely  ineffectual ;  whilst  in 
the  case  of  a  negative,  the  non-acidified  developer  would  be 
too  rapid  and  too  unmanageable. 

The  temperature  is  a  very  influential  item  in  modifying 
the  operation  of  development.  The  higher  the  temperature 
the  greater  the  quantity  of  acid  required  to  preserve  the  ex- 
act equilibrium  between  fogging  on  the  one  hand  and  defi- 
ciency of  development  on  the  other. 

The  principal  acids  used  for  this  special  purpose  are  acetic 
acid,  tartaric  acid,  citric  acid,  and  formic  acid.  The  latter 
may  be  regarded  at  the  same  time  a  developer  from  -  its 
power  of  reducing  metallic  salts,  and  from  its  analogy  to 
acetic  acid  as  a  check  upon  development. 

Acetic  Acid. 

Symbol,  C4  H3  03  HO.    Combining  Proportion,  60.   Specific  Gravity,  1.063. 

Acetic  acid  belongs  to  a  small  group  of  which  acetyle  is 
the  base  or  compound  radical  derivative  from  ethyle  by  the 
oxidation  of  two  equivalents  of  its  hydrogen  in  the  formation 
of  water.  When  alcohol  and  ether  burn  in  the  air  the  pro- 
ducts of  combustion  are  carbonic  acid  and  water.  But  some- 
times the  oxidation  of  the  hydrogen  alone  takes  place,  and 
water  only  is  formed,  together  with  a  small  series  of  new 
bodies  containing  the  same  number  of  equivalents  of  carbon. 
Some  of  the  substances  arise  from  the  decomposition  of  col- 
lodion, such  as  aldehyde,  etc.  This  acid  may  be  formed 
directly  from  the  oxidation  of  alcohol  or  by  substituting  two 
equivalents  of  oxygen  in  the  place  of  two  of  hydrogen. 
Platinum-black  acting  upon  the  vapor  of  alcohol  will  pro- 
duce this  reaction  ;  or  a  small  quantity  of  yeast,  or  almost 
any  other  nitrogenized  organic  material  undergoing  putre- 
factive decomposition,  added  to  dilute  alcohol  and  exposed 
to  the  air  induces  the  same  reaction.  In  this  manner  vinegar 
and  alecar  arise  from  the  slow  acetic  fermentation,  as  it  is 
denominated,  of  weak  wines  and  beer.  When  hard  dry 
wood  or  twigs,  or  oak,  beech,  etc.,  are  submitted  to  destruct- 
ive distillation  at  a  red  heat,  acetic  acid  is  one  of  the  pro- 
ducts of  the  distillate.    The  first  part  of  the  sour  liquor 


104 


REDUCING  AGENTS  DEVELOPERS. 


which  distills  over  by  a  second  operation  is  not  acetic  acid  ; 
the  second,  however,  contains  the  acid,  but  is  impure.  It  is 
now  saturated  with  hydrate  of  lime  or  carbonate  of  lime,  by 
which  process  acetate  of  lime  is  formed.  Sulphate  of  soda 
is  then  added  in  solution  to  the  acetate  of  lime  as  long  as 
any  precipitate  of  sulphate  of  lime  falls.  The  resulting  ace- 
tate of  soda  is  filtered  from  the  lime  salt,  and  evaporated  to 
its  crystallizing  point  and  then  set  aside  until  crystals  are 
formed.  The  latter  are  drained  as  much  as  possible  from 
the  water  and  adhering  tarry  liquor,  and  then  heated  cau- 
tiously to  fusion,  by  which  the  tar  is  decomposed  and  ex- 
pelled. The  fused  mass  is  again  dissolved  and  crystallized. 
By  decomposing  this  salt  by  means  of  an  equivalent  of  sul- 
phiiric  acid  and  by  distillation  we  obtain  strong  acetic  acid, 
which,  by  rectification  over  red  oxide  of  lead,  can  be  con- 
centrated so  as  to  yield  crystals  at  a  low  temperature.  This 
is  denominated  glacial  acetic  acid,  and  melts  into  a  colorless 
liquid  above  60°  Fahr.  It  boils  at  a  temperature  of  240°  ; 
its  vapor  is  inflammable.  It  mixes  in  all  proportions  with 
water,  alcohol,  and  ether.  The  acetates  are  very  numerous ; 
all  of  them  are  soluble ;  those  of  silver  and  mercury  the 
least  so. 

Its  photographic  uses  are,  as  above  described,  to  check 
the  vehemence  of  reduction  by  the  developers  ;  it  is  used 
also  to  acidify  the  nitrate  of  silver  bath  in  connection  some- 
times with  acetate  of  soda,  and  with  this  connection  it  is 
said  to  yield  much  sensitiveness  and  intensity  with  a  plain 
iodized  collodion. 

Formic  Acid, 

Symbol,  C2  H03  HO.    Combining  Proportion,  46.    Specific  Gravity,  1.235. 

This  acid  is  so  called  because  it  is  found  in  ants,  from  the 
Latin  of  which  the  word  is  derived.  It  bears  the  same  re- 
lation in  the  methyle  group  as  acetic  acid  does  in  the  ethyl e 
series  ;  acetic  acid  being  formed  by  the  substitution  of  two 
equivalents  of  oxygen  for  two  of  hydrogen  in  the  formula 
for  alcohol,  whilst  formic  acid  arises  from  the  substitution 
of  two  equivalents  of  oxygen  for  two  of  hydrogen  in  the 
formula  for  wood-spirit,  a  substance  very  analogous  to  alco- 
hol. This  acid  can  be  obtained  by  distilling  ants  in  water. 
It  is  an  organic  acid,  however,  which  can  be  formed  artifi- 
cially by  heating  organic  substances,  such  as  sugar,  starch, 
etc.,  with  oxidizing  agents.  Thus  :  mix  one  part  of  starch 
or  sugar  or  tartaric  acid  with  four  of  the  bin  oxide  of  man- 
ganese, four  of  water,  and  four  of  sulphuric  acid.    By  this 


REDUCING  AGENTS  DEVELOPERS. 


105 


mixture  carbonic  acid  will  be  liberated  with  effervescence. 
As  soon  as  this  is  over  the  materials  are  subjected  to  distill- 
ation until  four  parts  and  a  half  have  passed  over.  The  acid 
liquor  thus  obtained  is  impure  formic  acid,  which  is  purified 
by  neutralizing  it  with  carbonate  of  soda,  and  evaporating 
the  solution  so  as  to  obtain  formiate  of  soda  in  crystals 
which  may  be  freed  from  all  impurities  in  the  same  manner 
as  acetate  of  soda  in  the  preceding  paragraphs.  From  the 
pure  formiate  of  soda,  any  other  formiate,  or  formic  acid, 
may  be  obtained  by  neutralizing  the  formiate  with  sulphuric 
acid  and  by  distillation.  Hydrated  formic  acid  is  a  limpid, 
colorless  fluid,  of  an  intensely  pungent  odor ;  it  fumes  slight- 
ly ;  at  a  temperature  below  32°  Fahr.  it  crystallizes  in  bril- 
liant plates;  it  boils  at  212°.  It  produces  a  blister  on  the 
skin  when  concentrated.  In  very  many  respects  it  is  very 
similar  to  acetic  acid,  but  may  be  distinguished  from  the 
latter  by  its  comportment  with  oxide  of  silver  or  mercury, 
in  which,  when  heated,  it  reduces  the  metal  after  a  while 
and  liberates  carbonic  acid.  This  acid  is  obtained,  and  per- 
haps most  easily,  by  the  decomposition  of  oxalic  acid  in  con- 
tact with  glycerine  and  by  distillation. 

Photographic  Uses  of  Formic  Acid. 

From  the  similarity  between  acetic  and  formic  acid  it  may 
easily  be  inferred,  that  either  might  be  substituted  for  the 
other  in  the  developer,  but  the  reader  will  have  remarked  a 
decided  difference  in  their  action  on  silver  salts  ;  and  it  is 
just  on  these  salts  that  the  acid  is  brought  into  action  ;  it  is 
in  fact  an  excellent  reducing  agent,  and  when  heated  is  used 
by  several  distinguished  photographers  in  their  developing 
solutions,  of  which  the  formula  will  be  given  in  the  proper 
place. 

Citric  Acid. 
Symbol,  C12  Ho  0:1  +  3  HO +  2  Aq. 

This  acid  is  obtained  from  the  juice  of  limes,  lemons, 
orange,  currant,  quince,  cranberry,  red  whortleberry,  and 
other  fruits.  The  juice  is  imported  in  the  liquid  state  from 
the  West-Indies,  and  being  in  connection  with  much  mucil- 
age and  other  organic  impurities,  it  is  liable  to  undergo  de- 
composition on  the  way,  and  to  yield  in  the  preparation  of 
citric  acid  other  acids  endowed  with  different  properties. 
On  this  account  it  is  advisable  in  many  instances  for  the 
photographer  to  prepare  his  own  citric  acid. 


JOG 


REDUCING  AGENTS  DEVELOPERS. 


Preparation. 

Take  ten  ounces  of  expressed  lemon-juice  ;  boil  the  juice 
for  a  few  minutes,  then  add  to  it  after  it  is  cool  the  whites 
of  three  eggs,  and  stir  the  mixture  so  that  the  albumen  is 
intimately  broken  up  and  mixed  with  the  juice.  Boil  the 
mixture  again,  stirring  it  all  the  while,  and  allow  the  coagu- 
lum  to  settle.  When  cool,  filter  the  sour  liquor  and  boil  it 
again,  adding  to  it  gradually  powdered  chalk  as  long  as 
effervescence  is  produced  ;  citrate  of  lime  is  formed,  which  is 
but  sparingly  soluble  in  water.  The  dark-colored  mucilagi- 
nous liquor  is  filtered  off ;  the  residue  is  well  washed,  and 
afterward  decomposed  by  a  quantity  of  sulphuric  acid  equal 
in  weight  to  the  chalk  employed  in  the  previous  decomposi- 
tion. The  sulphuric  acid  is  diluted  with  about  seven  times 
its  weight  of  water ;  and  the  mixture  is  stirred  about  for 
some  time  until  the  citrate  of  lime  is  completely  decom- 
posed. By  filtration  the  citric  acid  is  separated  from  the 
insoluble  sulphate  of  lime,  and  is  afterward  evaporated 
until  a  pellicle  forms  on  its  surface  ;  it  is  then  set  aside  to 
crystallize.  The  dark-colored  crystals  are  removed  from 
the  supernatant  liquid  by  a  strainer  and  again  dissolved  in 
pure  water ;  the  liquid  is  again  evaporated  as  before,  until 
the  formation  of  a  pellicle  takes  place,  and  is  again  set  aside 
to  crystallize.  By  repeating  the  operation  several  times  the 
crystals  become  quite  clean  and  purified.  ■  Citric  acid  has  an 
agreeably  sour  taste  ;  like  phosphoric  acid  it  is  tribasic,  and 
gives  rise  to  three  classes  of  citrates.  It  is  soluble  in  less 
than  its  own  weight  of  cold  water,  and  in  half  its  weight  of 
boiling  water  ;  it  is  not  very  soluble  in  alcohol. 

Citrate  of  Soda. 
This  salt  is  prepared  by  dissolving  citric  acid  in  pure 
water  and  throwing  into  the  solution,  by  degrees,  pulver- 
ized carbonate  of  soda  as  long  as  effervescence  is  produced. 
The  liquid  is  afterward  evaporated  to  a  crystallizing  consist- 
ency and  then  set  aside.  In  this  case,  as  well  as  in  the  pre- 
ceding, the  mother-liquor  can  be  made  to  yield  new  crops 
of  crystals  by  further  evaporation  or  by  a  repeated  decom- 
position and  a  repetition  of  the  other  proceedings  arising 
out  of  it. 

Photographic  Uses  of  Citric  Acid. 
This  acid  is  frequently  mixed  with  pyrogallic  acid  in  pro- 
per quantity  for  solution  in  water  instead  of  acetic  acid.  It 
is  used  as  a  check  on  the  too  rapid  action  of  pyrogallic  acid, 
and  as  a  reducing  agent.    A  frequent  impurity  in  this  sub- 


REDUCING  AGENTS  DEVELOPERS. 


107 


stance  is  malic  acid,  and  sometimes  aconitic  acid.  Citric 
acid  is  recognized  by  its  producing  in  a  diluted  state  no  im- 
mediate precipitate  with  Chloride  of  Calcium  /  but  an  im- 
mediate precipitate  is  formed  when  the  solution  is  boiled. 

Tartaric  Acid. 

Symbol,  C8  H4  O10  +  2  Aq. 

This  acid  exists  in  combination  with  potassa  in  most  kinds 
of  fruit,  and  sometimes  in  a  free  state.  Its  combinations  in 
fruit  are  cream  of  tartar  and  tartrate  of  lime.  The  former 
exists  in  abundance  in  grape-juice,  and  is  denominated,  in 
the  crude  state,  Argol  or  Tartar,  which  is  either  red  or 
white  according  to  the  wine  from  which  it  is  deposited  dur- 
ing fermentation. 

Preparation  of  Tartaric  Acid. 

This  acid  is  obtained  from  argol,  or  from  cream  of  tartar, 
which  is  a  bitartrate  of  potassa,  by  two  processes  ;  one  con- 
sists in  abstracting  one  equivalent  of  tartaric  acid  from  the 
bitartrate,  and  the  other  in  decomposing  the  residual  tar- 
trate in  the  solution.  Following  the  formula  of  the  London 
College,  and  using  the  imperial  gallon,  which  contains  ten 
pounds  of  water,  the  method  stands  thus:  take  of  bitartrate 
of  potassa  four  pounds ;  boiling  distilled  water,  two  gallons 
and  a  half ;  prepared  chalk,  twenty-five  ounces  and  six 
drachms  ;  diluted  sulphuric  acid,  seven  pints  and  seventeen 
fluid  ounces ;  hydrochloric  acid,  twenty-six  fluid  ounces  and 
a  half,  or  as  much  as  may  be  sirfficient.  Boil  the  bitartrate 
of  potassa  with  two  gallons  of  the  distilled  water,  and  add, 
by  degrees,  the  half  of  the  chalk  ;  when  the  effervescence  is 
over,  add  the  remainder  of  the  chalk,  previously  dissolved  in 
the  hydrochloric  acid,  diluted  with  four  pints  of  the  distilled 
water.  Then  set  aside  until  the  tartrate  subsides  ;  after 
which  pour  off  the  liquor,  and  wash  the  tartrate  of  lime  fre- 
quently with  distilled  water  as  long  as  it  has  any  taste. 
Next  pour  on  the  diluted  sulphuric  acid,  and  boil  for  a 
quarter  of  an  hour.  Having  filtered  the  liquor  from  the  in- 
soluble sulphate  of  lime,  evaporate  it  by  a  gentle  heat  until 
a  pellicle  is  formed  on  its  surface  ;  then  set  it  aside  to  crys- 
tallize. By  dissolving  the  crystals  in  pure  water,  filtering, 
and  recrystallizing,  and  by  repeating  these  three  operations 
several  times,  pure  tartaric  acid  may  be  obtained. 

Tartaric  acid  is  not  volatile;  when  heated  it  leaves  an 
abundant  coaly  residue.  It  is  soluble  in  half  its  weight  of 
water ;  it  dissolves  also  in  alcohol.    The  salt  itself  under- 


108  REDUCING  AGENTS — DEVELOPERS. 

goes  no  change  when  exposed  to  the  atmosphere ;  but  its 
solution,  when  long  exposed,  absorbs  oxygen  and  forms 
acetic  and  carbonic  acid.  When  boiled  over  an  excess  of 
oxide  of  silver,  the  same  decomposition  is  produced,  and 
metallic  silver  is  liberated.'  When  fused  with  potassa  it  is 
decomposed  into  acetic  and  oxalic  acid  ;  whilst  with  bin- 
oxide  of  manganese  and  sulphuric  acid,  it  gives  rise  to  car- 
bonic and  formic  acid.  Concentrated  sulphuric  acid,  when 
heated  with  the  crystals  of  tartaric  acid,  decomposes  it  and 
separates  carbon,  which  renders  the  mixture  black  ;  and  car- 
bonic oxide  is  evolved  at  the  same  time,  which  burns  with  a 
blue  flame. 


CHAPTER  XV. 


THE  NITEATE  OF  SILVER  BATH. 

Nothing  can  be  easier  to  prepare  than  the  bath  of  nitrate 
of  silver,  and  yet  there  is  no  preparation  in  the  art  of  pho- 
tography which  produces  so  many  difficulties  and  troubles  to 
surmount  as  the  sensitizing  bath  for  the  iodized  ocbromo- 
iodized  collodion  plates.  In  consequence  of  this  it  becomes 
a  difficult  task  to  prescribe  rules  by  which  such  a  bath  can 
be  preserved  sensitive  under  the  troubles  with  which  it  is  so 
frequently  beset.  The  origin  of  these  troubles  may  be  traced 
to  the  materials  introduced  by  the  immersion  of  the  collo- 
dion plates ;  but  these  deteriorating  materials  are  of  such  a 
heterogeneous  nature,  arising  from  the  decomposition  of  the 
pyroxyline,  of  alcohol,  of  ether,  of  the  iodides,  the  bromides, 
their  bases,  and  of  the  elements  combining  with  them,  that 
it  is  as  yet  an  unsolved  problem,  that  of  determining  precise- 
ly the  cause  of  any  given  abnormal  action  in  the  nitrate  bath. 
It  is  true,  as  regards  the  introduction  of  injurious  substances 
into  the  bath,  all  effects  resulting  therefrom  can  be  avoided 
by  using  the  solution  of  nitrate  of  silver  only  once.  If  this 
salt  were  not  so  expensive,  this  mode  of  avoiding  trouble 
would  be  by  far  the  wisest  and  the  safest.  In  such  a  case 
the  photographer  would  flow  his  plate  with  the  silver  solu- 
tion in  the  same  manner  as  with  the  developing  or  fixing  so- 
lution, using  just  sufficient  to  cover  the  film  and  to  sensitize 
it.  All  the  residual  part  might  be  collected,  decomposed, 
and  fresh  nitrate  prepared.  But  because  the  silver  salt  is  a 
dear  material,  we  aim  to  economize  by  using  the  solution 
over  and  over  again.  For  this  purpose,  glass,  porcelain  or 
photographic-ware  baths  are  constructed  for  containing  the 
fluid.  They  are  made  so  as  to  accommodate  the  largest 
plate  with  the  least  quantity  of  the  solution,  a  great  mistake 
superinduced  by  false  economy.  In  this  country  vertical 
baths  seem  to  be  the  only  ones  employed  ;  whereas  in  France 
and  Germany,  for  economical  and  other  special  reasons  al- 
ready alluded  to,  horizontal  dishes  contain  the  solution,  and 


110 


THE  NITEATE  OF  SILVER  BATH. 


the  plates  lie,  as  it  were,  collodion  side  downward  in  a  thin 
layer  of  the  same.  Some  of  these  baths  are  especially  adapted 
for  the  tourist,  admitting  the  fluid  to  be  closed  hermetically 
by  means  of  India-rubber  caps,  screws  and  clamps.  Nitrate 
of  silver  will  permeate  through  the  parietes  of  porcelain  baths; 
the  photographic-ware  bath  and  the  glass  are  not  subject  to 
this  inconvenience. 

Preparation  of  the  Sensitizing  Solution. 
An  ounce  Avoirdupois  contains  437.5  grains  ;  the  druggists 
and  photographic  dealers  retail  all  their  chemicals  accord- 
ing to  this  weight,  and  not,  as  many  suppose,  according  to 
the  Troy  weight,  of  which  the  ounce  contains  480  grains. 
The  sensitizing  solution  is  found  by  experience  to  be  suffi- 
ciently strong  if  it  contain  from  35  to  40  grains  to  the  fluid 
ounce  of  water,  or  from  8  to  10  per  cent. 

Formula  No.  1. 

Nitrate  of  silver,  (recrystallized,)     .    .  3  ounces. 

Distilled  or  pure  rain-water,   36  ounces. 

Washed  iodide  of  silver,   6  grains. 

Washed  oxide  of  silver,   6  grains. 

Dissolve  the  nitrate  of  silver  in  half  the  water,  then  add  to  it 
the  washed  iodide  of  silver,  prepared  as  directed  on  a  preced- 
ing page,  afterward  add  to  the  mixture  the  six  grains  of  ox- 
ide of  silver,  which  is  prepared  as  follows  :  Take  a  solution  of 
ten  grains  of  nitrate  of  silver  and  drop  into  it  a  solution  of 
pure  caustic  potash,  as  long  as  a  brown  precipitate  is  formed. 
Then  filter  and  wash  the  brown  oxide  on  the  filter  many 
times  with  cold  water,  and  afterward  with  warm  water,  until 
the  filtrate  ceases  to  have  any  action  on  red  litmus  paper. 

The  mixture  is  now  boiled  in  a  large  glass  flask  on  a  sand- 
bath,  and  wrhen  cold  the  remaining  water  is  added  to  it,  and 
the  whole  of  it  is  filtered  through  a  double  filter  of  Swedish 
filtering  paper.  The  solution  so  prepared  will  be  saturated 
with  iodide  of  silver,  so  that  it  will  not  dissolve  any  of  the 
iodide  of  silver  on  the  collodion  film ;  it  will  be  besides  per- 
fectly neutral,  if  the  oxide  of  silver  has  been  thoroughly 
washed  from  any  adhering  alkali.  With  a  collodion  con- 
taining free  iodine,  either  from  decomposition  or  by  insertion, 
this  bath  is  exceedingly  sensitive,  and  produces  at  the  same 
time  clear  pictures.  For  colorless  collodions  it  is  not  suit- 
able, nor  for  collodions  which  are  quite  freshly  made,  with- 
out the  addition  of  iodine,  that  is,  for  those  which  have  not 
had  time  to  ripen,  as  it  is  termed  in  ordinary  language. 

For  such  collodions,  the  colorless  and  pale  colored  collo- 


THE  NITRATE  OF  SILVER  BATH. 


Ill 


dions,  containing,  as  they  generally  do,  cadmium  salts,  the 
following  bath  will  be  found  to  be  quite  effective  in  produc- 
ing good  results  : 

Formula  No.  2. 
Nitrate  of  silver,  (recrystallized,)     .    .      3  ounces. 

Distilled  or  rain-water,  36  ounces. 

Iodide  of  silver,  (washed,)     ....      6  grains. 

Mix  as  before,  and  filter  without  boiling.  For  each  ounce  of 
nitrate  of  silver  add  one  drop  of  nitric  acid.  This  amount  will 
probably  be  found  sufficient  to  produce  a  clear  picture ;  should 
the  picture  show  any  signs  of  fogging,  add  another  drop,  and 
so  proceed  until  the  details  of  the  development  appear  with- 
out a  universal  cloudiness  over  the  plate. 

Formula  No.  3. 

Nitrate  of  silver,  (recrystallized,)  .  .  3  ounces. 
Distilled,  or  pure  rain-water,  .  .  .  .36  ounces. 
Iodide  of  silver,  (washed,)   6  grains. 

Prepare  as  before,  and  after  filtration  divide  the  quantity  into 
two  lots  of  18  ounces  each.  Neutralize  one  of  these  with 
washed  oxide  of  silver  by  boiling,  and  then  filter.  Add  to 
the  other  18  drops  of  a  solution  of  acetate  of  soda,  (contain- 
ing 160  grains  to  the  ounce  of  water,)  and  10  drops  of  gla- 
cial acetic  acid.  Each  of  these  baths  may  be  used  separate- 
ly, or  in  mixture.  The  neutral  bath  is  kept  neutral  without 
admixture ;  but  to  the  second,  containing  the  acetate  of  soda 
and  accetic  acid,  a  portion  of  the  first  may  be  added  as  re- 
quired from  time  to  time,  if  it  is  found  to  work  too  slowly. 
As  a  general  thing  the  acetate  of  soda  bath  produces  very 
vigorous  pictures,  and  renders  the  collodion  film  quite  sensi- 
tive. 

In  summer  the  bath  need  not  be  so  strong  in  nitrate  of  sil- 
ver as  given  in  the  preceding  formulas.  Six  or  seven  grains 
of  silver  per  cent  of  the  water  will  be  sufficient  when  the 
temperature  is  high ;  on  the  contrary,  from  eight  to  ten  per 
cent  may  be  used  when  the  temperature  is  moderate  or  low. 
The  sensitizing  solution  works  quicker  when  warm  than  when 
cold. 

When  the  sensitizing  solution  becomes  weak  by  exhaus- 
tion, it  can  be  restored  to  a  good  working  condition  by  the 
addition  of  a  stronger  solution  of  nitrate  of  silver,  containing 
40  or  50  grains  to  the  ounce  of  water.  After  a  bath  has  been 
in  operation  for  some  time,  it  becomes  saturated  with  a  va- 
riety of  impurities,  such  as  ether,  alcohol,  acetic  acid,  aldehyde, 
the  various  nitrates  in  the  collodion,  and  a  variety  of  sub- 


112 


THE  NITRATE  OF  SILVER  BATH. 


stances  arising  from  the  decomposition  of  this  heterogeneous 
mixture.  The  best  way  to  get  rid  of  all  volatile  material  is 
to  subject  the  solution  to  distillation,  until  all  the  ether  and 
alcohol,  at  least,  have  been  expelled,  and  then  to  filter  the  res- 
idue in  the  retort,  and  to  mix  it  with  a  new  bath.  Although 
such  a  restored  bath  will  give  good  results  for  a  while,  it  soon 
gets  out  of  order,  and  can  no  longer  be  relied  upon.  In  such 
a  case  it  is  far  more  expedient  to  set  it  aside  for  reduction, 
and  to  form  a  totally  new  bath,  than  to  be  at  the  trouble  of 
a  second  distillation,  because  the  fixed  salts  have  accumulat- 
ed to  such  a  degree  as  to  render  the  bath  very  capricious  and 
unstable. 

When  a  bath  does  not  yield  clear  pictures  when  first  formed, 
or  ceases  to  do  so  after  a  given  time  with  the  same  collodion, 
or  happens  not  to  do  so  with  a  new  collodion,  it  is  advisable 
not  to  trifle  with  the  bath  by  adding  either  acid  or  alkali. 
It  may  be  well  to  ascertain  by  test-paper  whether  the  trouble 
is  attributable  to  alkalinity  or  acidity.  If  no  alkali  has  been 
added  to  the  bath,  it  will  probably  have  an  acid  reaction. 
In  this  case  it  is  preferable  to  boil  the  bath  with  the  washed 
oxide  of  silver,  as  before  prescribed,  and  then  to  filter  it. 
Should  the  bath  turn  out  to  be  neutral  to  test-paper,  it  will 
be  found  in  general  a  better  practice  to  add  a  few  drops  of 
tincture  of  iodine  to  the  collodion,  rather  than  to  acidify  the 
sensitizing  solution  ;  because  the  iodine  in  the  collodion  lib- 
erates an  acid  by  decomposition  on  and  in  the  film  of  collo- 
dion, which  rectifies  the  evil  where  the  rectification  is  wanted, 
and  at  the  proper  time,  without  changing  materially  the  con- 
ditions of  the  bath.  Thus  the  operator  will  learn  to  use  up 
a  highly  colored  collodion  by  mixing  it  gradually,  as  it  is 
wranted,  with  new  and  almost  colorless  collodions,  in  order 
to  clarify  his  pictures,  without  resorting  to  methods  of  at- 
taining to  the  same  result  by  adding  acid  to  the  bath. 

During  the  time  the  bath  is  in  use,  a  quantity  of  insoluble 
material  of  a  gray  or  violet-gray  color  is  precipitated  on 
the  bottom  and  sides  of  the  bath,  and  frequently  floats 
about  in  the  sensitizing  fluid.  The  particles  of  this  material, 
as  well  as  of  the  acicular  crystals  of  acetate  of  silver  in  a  weak 
bath  are  apt  to  attach  themselves  to  the  moist  collodion  film 
on  its  immersion,  and  thus  give  rise  to  the  innumerable  small 
apertures  sometimes  exhibited  on  the  developed  negative. 
These  particles  are  not  the  sole  cause  of  this  evil,  so  much 
dreaded  ;  but  they  frequently  cause  it  by  their  attachment  to 
the  film  during  the  exposure,  and  owing  to  their  opacity,  pre- 
vent the  actinic  action  from  taking  effect  on  the  film  be- 


THE  NITEATE  OF  SILVER  BATH.  113 

fieath,  and  becoming  loosened  by  the  developing  and  fixing 
solutions,  afterward  expose  the  transparent  parts  on  which 
they  had  rested.  It  is  advisable,  therefore,  to  expose  the 
bath  in  a  glass  vessel  to  the  rays  of  the  sun  as  often  as  possi- 
ble, in  order  that  the  organic  matter  may  be  precipitated. 
The  bath,  too,  ought  to  be  filtered  very  frequently  in  the 
same  filter,  at  least  once  a  week ;  and  if  every  evening,  so 
much  the  better.  After  filtration  the  bath  can  be  strength- 
ened by  an  addition  of  fresh  solution,  in  proportion  to  the  daily 
work  performed.  See,  during  filtration,  that  the  sides  and 
the  bottom  of  the  vessel  are  perfectly  clean  before  the  solu- 
tion is  poured  back  again.  A  long  thin  wooden  spatula,  with 
a  piece  of  sponge  at  the  end,  will  be  found  very  convenient 
for  clearing  away  the  adhering  gray  deposit.  Use  only  rain- 
water for  rinsing  ;  rinse  thoroughly ;  then  turn  the  bath  wrong 
side  up,  and  rear  it  on  one  corner,  in  order  that  every  drop 
of  water  may  thus  be  removed.  Wipe  the  edges  before  the 
sensitizing  fluid  is  again  introduced.  This  exposure  to  the 
rays  of  the  sun,  and  frequent  filtration  will  remedy  in  a  great 
measure  the  trouble  alluded  to,  and  there  is  no  fear  of  in- 
juring the  property  of  the  solution,  for  nitrate  of  silver  alone 
is  not  acted  upon  by  light,  does  not  change  at  all  when  pure. 

By  exposing  the  solution  in  a  vessel,  such  as  a  glass  eva- 
porating dish,  much  of  the  superfluous  ether  and  alcohol  will 
pass  off  in  vapor,  and  thus  produce  a  remedy  for  another  evil 
which  an  old  bath  invariably  gives  rise  to,  namely,  that  of 
causing  oily-looking  stains  and  streaks  on  the  surface  of  the 
film. 

Where  the  trouble  of  recrystallizing  the  nitrate  of  silver 
would  be  deemed  too  great,  and  neutral  nitrate  of  silver 
can  not  easily  be  purchased,  I  would  recommend  that  the 
photographer  should  fuse  the  nitrate  of  silver  in  a  porcelain 
evaporating  dish,  at  a  gentle  heat,  and  afterward  pour  out  the 
fused  mass  on  a  silver  or  marble  plate,  as  directed  in  the 
manufacture  of  lunar  caustic.  The  same  proportions  of  the 
fused  nitrate  are  used  as  in  the  formulas  for  the  recrystallized 
nitrate.  Or  a  strong  solution  of  the  nitrate  may  be  boiled  with 
the  washed  oxide  of  silver,  filtered,  and  evaporated  to  dry- 
ness, and  used  in  the  same  way. 


CHAPTER  XYI. 


THE  DEVELOPING  SOLUTIONS. 


In  the  ordinary,  or  wet-collodion  process,  there  are  three 
Developing  Solutions,  the  Protosulphate  of  Iron  Developer, 
the  Pyrogallic  Acid  Developer,  and  the  New  Developer, 
with  the  double  salt  of  the  sulphate  of  the  protoxide  of  iron, 
and  the  sulphate  of  ammonia. 

Sulphate  of  Iron  Developer. 
Formula  Wo.  1.    For  Ambrotypes  and  Melainotypes. 
Crystals  of  the  protosulphate  of  iron,  .    3  drachms. 


Pulverize  the  iron  salt,  if  it  has  not  been  precipitated  in  al- 
cohol, and  mix  it  intimately  with  the  rain-water  in  the  mor- 
tar ;  then  add  the  acid  and  the  alcohol,  and  see  that  the  so- 
lution is  complete  ;  then  filter  and  use.  From  a  previous  ob- 
servation on  the  subject  of  developing,  it  will  be  conceived 
that  the  quantity  of  acid  must  vary  according  to  several  cir- 
cumstances. In  summer,  that  is,  when  the  temperature  is 
high,  more  acid  will  be  required  to  keep  the  reducing  agent 
in  check ;  in  like  manner,  if  the  time  of  exposure  has  been 
too  long,  the  development  or  decomposition  is  more  easily 
accomplished,  and  on  this  account  more  acid  is  required.  On 
the  contrary,  in  winter,  when  the  temperature  is  low,  as  also 
when  the  time  has  been  very  short,  as  for  example,  for  in- 
stantaneous operations,  the  proportion  of  acid  may  be  dimin- 
ished, until  finally  the  solution  of  the  iron  salt  may  be  used 
without  any  acid.  In  such  cases  it  is  well  to  have  a  bath  of 
the  solution,  into  which  the  exposed  plate  can  be  immersed 
almost  instantaneously,  and  treated  with  the  ordinary  acid 
solution  afterward.  Considerable  dexterity  is  required  in 
this  twofold  operation.  Of  course  diminishing  the  iron  salt, 
or  increasing  the  acid  are  correlative  expressions,  and  signify 
almost  the  same  thing,  the  slight  difference  depending  upon 


Rain-water, 
Acetic  acid, 
Alcohol,  . 


4  ounces. 
3  drachms. 
2  drachms. 


THE  DEVELOPING  SOLUTIONS. 


115 


the  influence  of  the  water  which  remains  stationary,  or  rela- 
tively increases  sometimes  in  favor  of  the  iron,  and  some- 
times of  the  acid. 

Formula  No.  2.    For  Negatives. 

Crystals  of  the  sulphate  of  the  protoxide  of  iron,  .  2  drachms. 

Distilled,  or  rain-water,   32  drachms. 

Acetic  acid,   3  drachms. 

Alcohol,   3  drachms. 

Pulverize  and  mix  as  before.  A  negative  requires  a  longer 
exposure  than  the  ambrotype,  or  the  melainotype ;  the  iron, 
therefore,  is  diminished  whilst  the  other  ingredients  remain 
the  same.  In  the  first  formula  a  drop  or  two  of  pure  nitric 
acid  may  be  added,  because  it  produces  a  more  reguline 
reduction  of  the  silver  salt,  and  leaves  a  very  beautifully 
white  metallic-looking  film  where  the  light  has  acted.  Too 
much  nitric  acid  would  spoil  the  picture  by  producing  too 
intense  a  reduction,  accompanied  with  irregularity  of  depo- 
sition. 

Formula  No.  3.    For  Negatives. 
Pyrogallic  acid,  (pure,)     .    .    .  .24  grains.  )    N    %  g  j  . 
Acetic  acid,  2  ounces.  J 

Shake  the  solution  well,  and  keep  in  a  dark  place. 

Of  No.  1  Solution,     ....      2  drachms.  )  n  «  ,  . . 

Distilled  water,  .'  14  drachms.  [   Na  2  Solutlon' 

The  reduction  by  this  developer  is  quite  appropriate  for  ne- 
gatives ;  its  color  is  grayish,  but  not  metallic  in  appearance. 
This  developer  is  very  manageable,  and  very  successful.  It 
requires,  however,  a  longer  exposure  than  the  iron  develop- 
er, in  the  ratio  of  three  to  one,  from  my  own  experience  in 
out-door  photography.  It  is  not  so  apt  to  fog  a  picture  as 
the  iron  developer. 

Formula  No.  4.    For  Negatives. 
teaac!rid'.         SEtl  Divide  into  doses  of  2  grains. 

When  required,  dissolve  a  two-grain  dose  of  the  preceding 
in  four  drachms  of  distilled  water.  The  amount  of  citric 
acid  can  be  modified  according  to  the  same  circumstances 
which  regulate  the  treatment  with  acetic  acid. 

DisderVs  Developer. 

Sulphate  of  the  protoxide  of  iron,    ...     4  drachms. 

Water,  12  ounces. 

Acetic  acid,  4  drachms. 


116 


THE  DEVELOPING  SOLUTIONS. 


Lieut.-  Colonel  Stuart  Wbrtley's  Developer. 

Sulphate  of  iron,   20  ounces, 

Distilled  water,  120  ounces. 

Dissolve. 

Acetate  of  lead,  -J  ounce. 

Water,    .    . "  5  ounces. 

Dissolve. 

Mix  the  above  solutions,  and  as  soon  as  the  precipitate  has 
settled,  decant  off  very  carefully.  Add 

Formic  acid,  5  ounces. 

Acetic  ether,  1-J  ounces. 

Mtric  ether,   " 

This  mixture  is  the  stock  solution,  from  which  a  portion  is 
taken,  when  required,  and  filtered  for  use. 

Meynier's  Developer. 

Double  sulphate  of  the  oxide  of  iron  and  ammonia,  .    100  grains. 

"Water,  23  ounces. 

Acid  acetic,  4  to  8  drachms. 

Alcohol,  4  " 

Or  the  preceding  formula  may  stand  as  follows : 

Sulphate  of  the  protoxide  of  iron,  69  grains. 

Sulphate  of  ammonia,  37  " 

Water,  24  ounces. 

Acetic  acid,  4  to  8  drachms. 

Alcohol,  4  drachms. 

Hoclrin's  Developer. 

Formic  acid,  (strong,)  2  drachms. 

Pyrogallic  acid,   20  grains. 

Distilled  water,   9J-  ounces. 

Alcohol,  i  ounce. 

This  developer  is  poured  upon  the  plate,  and  kept  there  un- 
til the  intensity  is  deep  enough.  It  acts  more  quickly  than 
the  pyrogallic  acid  containing  acetic  acid,  but  less  so  than 
the  iron  developer  ;  but  it  is  less  liable  to  fog  than  the  iron 
developer,  and  can  consequently  be  retained  longer  on  the 
plate. 

Waldack's  Formulas  for  Collodion  Positives. 

Formula  No.  1.    For  Dead -Whites. 

Sulphate  of  iron,  3  drachms. 

Water,  6£  ounces. 

Acetic  acid,  4  drachms. 

Alcohol,  3  drachms. 

Nitrate  of  potassa,  30  grains. 


THE  DEVELOPING  SOLUTIONS.  117 

Formula  No.  2.    For  Brilliant  and  Metallic  Whites. 

Sulphate  of  iron,  85  grains. 

Water,  6£  ounces. 

Acetic  acid,  1  drachm. 

Alcohol,  1£  drachms. 

Nitrate  of  potassa,  SO  grains. 

Solution  of  nitrate  of  silver,  30  grains. 

Nitric  acid,  10  drops. 


In  all  the  preceding  formulas,  alcohol  may  or  may  not  be 
added,  according  to  circumstances.  It  is  used  when  the  de- 
veloper does  not  flow  easily  over  the  plate,  forming,  as  it 
were,  oily  streaks  on  the  surface.  It  remains,  therefore,  with 
the  artist  to  use  or  reject  it,  as  it  may  be  found  necessary. 


CHAPTER  XVII. 


s  FIXING  SOLUTIONS. 

Fixinq  solutions  consist  of  chemical  substances  that  dis- 
solve the  sensitized  salts  of  silver  on  plates  or  paper,  on  which 
photographic  images  have  been  developed.  The  parts  which 
form  the  image  are  covered  with  reduced  silver,  or  an  altered 
iodide  or  chloride  of  silver,  which  is  insoluble  in  the  fixers ; 
whereas  those  parts  which  have  not  been  impressed  by  the 
actinic  rays  are  made  transparent  with  the  fixing  solutions, 
which  dissolve  the  opaline  silver  compounds,  and  cause  the 
picture  afterward  to  be  unchangeable  when  exposed  to  light. 
The  fixing  solutions  at  present  in  use  are :  Cyanide  of  po- 
tassium, Hyposulphite  of  soda,  and  Sulphocyanide  of  ammo- 
nium. 

Cyanogen. 

Symbol,  C2N,  or  Cy.  Combining  Proportion,  26.   Spec.  grav.  1.819. 

This  Substance  is  properly  a  Bicarbide  of  Nitrogen ;  it  is  a 
1  very  important  material,  as  being  the  type  of  what  are  de- 
nominated compound  salt-radicals ;  it  was  the  first  of  this 
class  of  bodies  discovered.  Cyanogen  is  always  produced  in 
combination  when  an  alkaline  carbonate  is  heated  with  or- 
ganic matter  containing  nitrogen.  It  does  not  exist  either 
in  a  free  or  combined  state  in  nature ;  it  is  a  production  of 
decomposition,  in  which  the  elements  contained  in  it  are 
brought  together  in  the  nascent  state,  in  connection  with 
some  metallic  base: 

Preparation  of  Cyanogen. 
This  compound  radical  is  obtained  by  heating  either  a  cya- 
nide of  silver  or  of  mercury  in  a  flask  of  hard  glass  ;  a  gas, 
the  substance  in  question,  is  produced,  which  may  be  col- 
lected, by  reason  of  its  greater  specific  gravity  than  air,  in 
a  tall  glass  jar,  by  directing  the  outlet  tube  to  the  bottom"; 
or  it  may  be  collected  over  mercury.  It  is  colorless,  but  its 
odor  is  quite  peculiar  and  characteristic.  It  burns  with  a 
peach-colored  flame,  yielding  carbonic  acid  and  nitrogen. 
Water  dissolves  four  volumes  of  this  gas;  and  alcohol  as 
much  as  twenty-five  volumes.    An  aqueous  solution  is  de- 


FIXING  SOLUTIONS. 


119 


composed  when  exposed  to  light  into  a  variety  of  ammonia- 
cal  compounds.  By  the  pressure  of  four  atmospheres  it  is 
reduced  to  the  liquid  state.  It  combines  with  alkaline  solu- 
tions precisely  in  the  same  way  as  chlorine,  iodine  and  bro- 
mine, and  gives  rise  to  salts  denominated  cyanides. 

Hydrocyanic  Acid — Prussic  Acid. 
Symbol,  H  Cy. 

This  acid  is  obtained  from  the  cyanides  or  the  ferrocyan- 
ides  by  the  superior  affinity  of  the  mineral  acids  for  their 
bases  in  a  manner  similar  to  that  by  which  the  other  hy- 
dracids  are  obtained.  Take,  for  instance,  three  parts  of  the 
yellow  prussiate  of  potash  (ferrocyanide  of  potassium)  in 
fine  powder,  two  parts  of  sulphuric  acid,  and  two  of  water, 
and  distill  the  mixture  in  a  flask  or  retort;  the  vapor  which 
passes  over  is  condensed  in  a  receiver  surrounded  by  ice. 
Prussic  acid  is  a  colorless  liquid  of  the  specific  gravity  of 
0.6969.    It  is  exceedingly  poisonous. 

Cyanide  of  Potassium. 
Symbol,  K  Cy. 

This  substance,  so  exceedingly  useful  to  the  photographer, 
might  be  formed  by  passing  the  vapor  of  hydrocyanic  acid 
through  a  solution  of  potassa  to  saturation,  and  then  evapo- 
rating to  dryness  without  access  of  air.  It  is  formed,  how- 
ever, by  heating  ferrocyanide  of  potassium  in  an  iron  bottle 
to  an  intense  red  heat ;  the  tube  of  the  bottle  dips  into  water 
to  conduct  away  the  gases.  The  cyanide  of  iron  becomes 
decomposed  into  carbide  of  iron  and  charcoal,  and  its  nitro- 
gen is  given  off,  whilst  the  cyanide  of  potassium  remains  un- 
decomposed,  and  when  melted  swims  on  the  surface  of  the 
porous  black  mass  below.  It  is  afterward  pulverized  and 
dissolved  in  boiling  weak  alcohol,  from  which  it  crystallizes 
as  the  alcohol  cools  ;  or  whilst  in  a  fused  condition  it  is 
poured  upon  marble  slabs  and  afterward  broken  up  and 
bottled.  This  substance  is  almost  as'  poisonous  as*  hydro- 
cyanic acid,  but  being  a  fixed  salt  it  is  easily  detected  in 
the  stomach  ;  whereas  hydrocyanic  acid,  by  reason  of  its 
volatility,  seldom  leaves  any  trace  behind  by  which  the 
cause  of  death  can  be  reqognized.  This  salt  is  decomposed 
by  the  red  oxide  of  mercury  into  cyanide  Of  mercury  and 
potassa,  showing  the  superior  affinityof  cyanogen  for  mer- 
cury. On  this  account  the  ordinary  tests  for  mercury  do 
not  act  on  cyanide  of  mercury,  with  the  exception  of  hydro- 
sulphuric  acid  ;  analogous  to  hyposulphite^  of  silver- in  which 
hydrochloric  acid  "or  a  soluble  chloride  does  not  precipitate 


120 


FIXING  SOLUTIONS. 


the  chloride  of  silver,  hydro  sulphuric  acid  alone  being  capa- 
ble of  forming  a  precipitate. 

Sulphocyanide  of  Potassium.  • 
Symbol,  Cy  Sa  K. 

This  salt  is  obtained  by  a  process  similar  to  the  last  with 
an  addition  of  sulphur  to  the  amount  of  half  the  weight  of 
the  ferrocyanide  of  potassium  used.  It  is  an  excellent  test 
of  the  persalts  of  iron,  with  which  it  produces  blood-red  pre- 
cipitates. I  do  not  see  why  this  salt  may  not  be  used  in- 
stead of  the  following  as  a  fixer ;  it  certainly  can  be  more 
easily  procured,  and  is  no  doubt  just  as  poisonous. 

Sulphocyanide  of  Ammonium. 
Symbol,  Cy  S2  NHv 
This  is  the  new  fixing  salt  of  Meynier  which  is  said  to  be 
endowed  with  properties  for  photographic  purposes  as  pow- 
erful as  those  of  cyanide  of  potassium,  without  having  the 
poisonous  and  otherwise  deleterious  properties  of  this  salt. 
Meynier,  I  think,  must  have  made  a  mistake  as  to  this  latter 
property.  Sulphocyanide  of  ammonium  may  be  formed  by 
distilling  the  vapor  of  hydrocyanic  acid  into  a  solution  of 
sulphide  of  ammonium  and  evaporating  the  solution  at  a 
very  gentle  heat ;  or  still  better  by  neutralizing  hydrosul- 
phocyanic  acid  by  means  of  potassa. 

HydrosulpJiocyanic  Acid. 
Symbol,  Cy  S2  H. 

This  acid  is  analogous  w^ith  the  hydracids  ;  it  is  obtained 
as  a  colorless  liquid  by  decomposing  sulphocyanide  of  lead 
by  means  of  dilute  sulphuric  acid ;  and  sulphocyanide  of 
lead  results  from  the  decomposition  of  sulphocyanide  of  po- 
tassium with  acetate  of  lead. 

Hyposulphite  of  Soda. 
Symbol,  N4  0,  S2  0*. 

This  very  important  salt  is  obtained  by  digesting  sulphur 
in  a  solution  of  sulphite  of  soda,  which  dissolves  a  portion 
of  sulphur.  By  slow  evaporation  the  salt  crystallizes.  Hy- 
posulphurous  acid  can  not  be  isolated  from  any  of  its  com- 
binations. When  this  salt  is  pure  it  produces  no  precipitate 
with  nitrate  of  baryta.  The  crystals  contain  five  equivalents 
of  water,  and  are  soluble  in  a  very  high  degree  in  this  men- 
struum.   Its  taste  is  nauseous  and  bitter. 

The  photographic  properties  of  the  three  salts,  whose  pre- 
parations have  been  just  indicated,  are  to  dissolve  the  chlo- 
ride, iodide,  and  bromide  of  silver  in  their  recently  formed 


FIXING  SOLUTIONS. 


121 


state,  without  acting  as  solvents  on  the  altered  chloride, 
iodide,  and  bromide,  after  decomposition  by  light  and  de- 
velopers. In  all  cases  of  solution  they  form  cyanide,  sulpho- 
cyanide,  or  hyposulphite  of  silver,  which  frequently  enters 
into  combination  with  the  solvent  and  gives  rise  to  a  double 
salt,  as  the  hyposulphite  of  silver  and  the  hyposulphite  of 
soda,  together  with  either  chloride,  bromide,  or  iodide  of 
sodium.  Chloride  and  bromide  of  silver  are  soluble  to  a 
gfeater  extent  than  iodide  of  silver  in  hyposulphite  of  soda. 
Cyanide  of  potassium  is  not  only  a  solvent  of  the  silver  salts 
above  mentioned,  but  also  a  reducing  agent ;  it  thus  pro- 
duces in  the  ambrotype  and  the  melainotype  a  whiteness  in 
the  silver  film  which  can  not  be  effected  with  hyposulphite 
of  silver.  For  this  reason  it  is  regarded  by  many  photo- 
graphers as  the  fixing  agent  peculiarly  adapted  for  collodion 
positives  by  reflected  light ;  whereas  in  the  negative,  where 
the  whiteness  of  the  silver  film  is  of  little  or  no  consequence, 
hyposulphite  of  soda  is  regarded  as  the  proper  fixer.  Many 
photographers  disregard  these  refined  distinctions,  and  use, 
in  consequence  of  the  superior  solvent  properties  of  cyanide 
of  potassium,  this  substance  as  a  fixing  agent  indifferently 
for  negatives  and  positives.  But  because  cyanide  of  potas- 
sium dissolves  the  silver  salts  so  easily,  it  has  to  be  used  in 
a  dilute  condition,  and  to  be  watched  very  closely,  other- 
wise it  will  dissolve  at  the  same  time  the  fine  parts  of  the 
image.  Another  reason  why  cyanide  of  potassium  is  pre- 
ferred in  all  collodion  operations,  arises  from  the  difficulty 
of  washing  the  hyposulphite  of  soda  and  of  silver  from  the 
collodion  film ;  for  if  any  trace  of  these  salts  be  left,  the  col- 
lodion film  will  eventually  be  destroyed  by  crystallization 
taking  place  on  its  surface,  accompanied  with  a  decoloration 
and  soiling  of  the  image. 

Formula  No.  1. 
Fixing  Solution  with  Cyanide  of  Potassium. 


Cyanide  of  potassium,  1  drachm. 

Rain-water,  4  ounces. 

Formula  No.  2. 

Fixing  Solution  with  Hyposulphite  of  Soda. 

Hyposulphite  of  soda,  2  ounces. 

Water,  4  u 

Formula  No.  3. 
Fixing  Solution  with  Sulphocy anide  of  Ammonium. 

Sulphocyanide  of  ammonium,   1  drachm. 

Water,  12  ounces. 

6 


CHAPTER  XVIII. 


INTENSIFIERS. 

Intensifiers  are  substances  which,  when  applied  in  solu- 
tion to  the  developed  image,  increase  the  opacity  of  the 
shadows  and  middle  tints,  rendering  them  more  imperme- 
able to  light  in  direct  positive  printing.  With  a  proper  ad- 
justment of  light  and  developer,  and  especially  in  ordinary 
landscape-photography,  an  intensifier  is  seldom  needed ;  but 
many  artists  prefer  the  use  of  the  intensifier  on  every  occa- 
sion; they  maintain  that  a  negative  can  always  be  preserved 
as  clear  and  transparent  in  the  lights  as  a  positive  by  this 
process,  and  yet  the  density  of  the  shadows  may  be  increased 
to  any  extent  without  any  fear  of  fogging.  The  intensifying 
process  becomes,  therefore,  a  fixed  part  in  the  preparation 
of  a  negative.  The  operation  is  partly  physical  and  partly 
chemical ;  physical,  because  whatever  may  have  been  the 
action  of  the  light  on  those  parts  in  which  the  image  is  now 
apparent,  they  seem  still  to  be  endowed  with  properties  of 
attraction  of  an  intensity  in  proportion  to  the  development 
produced,  just  as  they  were  at  the  commencement  of  reduc- 
tion ;  but  the  nitrate  of  silver,  iodide  or  bromide  of  silver, 
having  been  exhausted,  the  application  of  any  developer, 
however  sensitive  or  intense,  could  produce  no  more  opacity 
on  the  shadows  for  want  of  material  to  be  reduced  —  but, 
mark  it  well,  the  physical  condition  is  there  to  institute  this 
reduction  the  moment  material  is  supplied. 

From  my  preceding  remarks  it  is  supposed  that  the  de- 
veloped image  consists  of  reduced  silver,  or  an  altered  salt 
of  silver  very  different  from  any  with  which  we  are  ac- 
quainted ;  there  is  no  more  iodide  or  nitrate  of  silver  ;  these 
have  been  removed  in  the  fixing  and  washing.  Now  in  order 
to  restore  the  partially  developed  image  to  the  chemical  con- 
dition requisite  for  the  recommencement  of  the  development, 
a  solution  of  iodine  in  iodide  of  potassium,  or  a  dilute  solu- 
tion of  tincture  of  iodine,  is  flowed  over  the  plate,  and  kept 
in  motion  over  the  image  in  order  to  preserve  uniformity 


INTEXSIFIEKS. 


123 


of  action.  The  iodine  thus  coming  in  contact  with  the 
silver  shadows  enters  into  combination  with  this  metal, 
and  forms  a  new  and  thicker  deposit  of  iodide  of  silver 
with  all  the  gradations  of  opacity  of  the  image,  and  not  a 
uniform  film  of  deposit.  The  solution  of  iodine  on  the  col- 
lodion loses  color  all  the  while ;  but  the  collodion  film  as- 
sumes at  first  a  grayish  and  then  a  yellowish-gray  hue. 
Even  at  this  stage  there  is  much  more  opacity  in  the  shadows  of 
the  picture  than  before,  and  the  negative  by  this  proceeding 
may  probably  be  dense  enough;  if  not,  proceed  to  the  second 
stage.  The  first  stage  is  the  depositing  stage ;  the  second, 
the  reducing  or  developing  stage  proper ;  and  yet  this  de- 
posit of  the  first  stage  is  a  chemical  combination  of  iodine 
and  silver  which  is  now  soluble  in  the  fixing  solutions,  and 
before  it  was  not.  By  this  process  of  depositing  and  fixing, 
and  by  regulating  the  quantity  of  the  iodine  solution,  a  nega- 
tive which  is  too  opaque  may  be  rendered  more  transparent 
and  less  dense  ad  libitum.  Osborne  has  availed  himself  of 
this  property  to  clarify  his  negatives  for  the  photolithographic 
process ;  I  would  recommend  it  also  in  the  preparation  of 
clear  and  sharp  negatives  for  obtaining  enlarged  positives 
in  the  solar  camera.  As  soon  as  the  depositing  stage  is 
complete,  and  the  film  has  been  washed,  the  collodion  film 
is  ready  for  the  reception  of  the  next  operation. 

The  second  stage  consists  in  communicating  to  the  iodized 
image  a  minute  quantity  of  nitrate  of  silver,  either  alone  and 
diluted,  or  in  connection  with  the  developer  ;  it  is,  in  fact,  a 
mere  repetition  of  the  original  process  of  development ;  the 
surface  of  the  collodion  is  in  the  same  condition  as  at  the 
commencement  when  it  left  the  camera ;  there  are  present 
iodide  of  silver,  nitrate  of  silver,  iodide  of  potassium,  the 
peculiar  and  unknown  physical  attraction  existing  in  the 
formed  image,  where  before  the  image  as  yet  was  unformed, 
and  the  developing  solution  either  of  sulphate  of  iron  or 
pyrogallic  acid.  The  second  stage  is  then  a  system  or  pro- 
cess of  redevelopment.  By  this  operation  the  intensity  may 
be  increased  to  any  extent ;  the  shadows  can  be  made  quite 
opaque  and  utterly  impermeable  to  the  actinic  influence. 
The  intensifying  part  of  the  collodion  process  is  very  much 
in  the  power  of  the  artist ;  success,  therefore,  will  depend 
principally  on  the  artistic  condition  of  what  I  denominate 
the  Foundation  Negative.  If  the  foundation  negative,  how- 
ever thin  the  shadows  maybe,  contain  lights,  shades,  and 
middle  tones  in  perfect  detail,  then  the  artist  has  it  in  his 
power  to  raise  these  three  conditions  gradually  and  uni- 


124 


INTENSIFIED. 


formly  higher,  until  the  shadows  become  endowed  witli  a 
proper  opacity.  At  the  end  of  this  stage  fixing  solutions 
have  but  little  effect,  which  seems  to  demonstrate  that  the 
yellowish-gray  iodide  has  been  converted  into  an  insoluble 
metallic  film  or  an  unknown  insoluble  silver  salt.  It  is  not 
necessary  to  use  the  fixing  solution.  All  that  is  required  is 
to  wash  the  image  well  before  it  is  dried  and  varnished. 

Other  deposits  and  other  metals  may  be  introduced  in  the 
intensifying  operations,  which  will  be  found  described  below. 

From  the  recent  experiments  and  observations  of  Blon- 
quart  Evrard,*  it  appears  that  a  negative  may  be  intensified 
by  a  second  exposure  to  light  before  fixing.  Thus,  suppos- 
ing a  negative  be  developed  as  far  as  it  seems  possible  to 
carry  on  the  reduction,  in  this  condition  let  it  be  exposed 
for  a  short  time  to  diffused  light.  This  physical  force,  it 
is  said,  again  acts  actinically,  but  now  only  upon  the  parts 
which  contain  the  image,  communicating  to  these  new  vigor, 
and  a  fresh  impulse,  which,  on  the  application  of  the  devel- 
oper, again  will  assist  in  the  formation  of  further  reduction. 

As  soon  as  the  image  has  been  fixed,  as  in  the  first  exam- 
ple, it  is  sometimes  flowed  with  a  saturated  solution  of  bi- 
chloride of  mercury,  by  which  probably  the  bichloride  is  re- 
duced to  the  protochloride,  and  the  liberated  chlorine  goes 
over  to  the  silver,  and  forms  chloride  of  silver.  This  appli- 
cation communicates  a  whiteness  to  the  image,  and  thickens 
the  deposit.  When  the  negative  has  been  washed,  it  is  flowed 
with  an  iodizing  solution,  containing  five  per  cent  of  iodide  of 
ammonium  in  water.  In  this  way  the  image  becomes  con- 
verted into  a  double  iodide  of  silver  and  mercury,  which, 
when  washed,  is  treated  with  the  iron  or  pyrogallic  devel- 
oper, containing  a  few  drops  of  nitrate  of  silver,  as  before. 
It  frequently  happens  in  this,  as  in  the  preceding  case,  that 
the  film  at  the  end  of  the  first  stage  is  opaque  enough.  In 
this  case  it  may  be  rendered  black  by  flowing  it  with  ammo- 
nia, hyposulphite  of  soda,  or  cyanide  of  potassium. 

A  third  method  of  strengthening  the  dark  parts  of  a  ne- 
gative takes  advantage  of  the  alkaline  sulphides,  which  con- 
vert the  developed  film  into  a  sulphide.  By  this  operation, 
however,  the  film  as  a  rule  is  not  increased  in  thickness,  its 
color  alone  being  changed,' which  is  frequently  more  agreea- 
ble to  look  at,  and  apparently  more  dense,  because  it  is  black, 
or  bluish-black.  These  alkaline  sulphides  may  be  used  with 
advantage  at  the  end  of  the  first  stage  or  deposit,  in  order 


*  Vide  Humphrey's  Journal.    Vol.  XV.    No.  1. 


INTENSIFIERS. 


125 


to  blacken  this  deposit ;  but  by  this  mode  of  intensifying 
there  is  a  great  liability  to  unequal  action,  to  decomposition 
after  the  negative  is  varnished,  to  contraction  of  the  collo- 
dion film,  and  its  separation  from  the  glass  ;  besides  this,  sul- 
phur seems  to  be  precipitated  sometimes  in  very  irregular 
patches,  giving  a' speckled  appearance  to  the  negative. 

Preparation  of  Bichloride  of  Mercury — Corrosive 
Sublimate. 

Symbol,  Hg.  CI.    Combining  Proportion,  136.9.     Spec,  grav.,  5.4. 

Dissolve  red  oxide  of  mercury  in  hydrochloric  acid;  eva- 
porate and  crystallize  ;  or  sublime  a  mixture  of  equal  weights 
of  sulphate  of  mercury  and  common  salt  in  a  stoneware  re- 
tort by  heating  to  redness  in  a  sand-bath.  The  bichloride, 
being  volatile,  passes  out,  whilst  sulphate  of  soda  remains 
behind  in  the  retort.  This  substance  melts  at  509°,  and 
boils  at  563° ;  it  dissolves  in  twenty  parts  of  cold  water,  in 
two  parts  of  boiling  water,  in  two  and  one  third  of  cold  al- 
cohol, and  in  three  of  cold  ether.  When  hydrosulphuric  acid 
is  passed  through  a  solution  of  this  salt,  a  brownish  preci- 
pitate is  first  formed,  which  eventually  becomes  quite  white. 
This  is  a  chlorosulphide. 

Preparation  of  Sulphide  of  Potassium — Hepar  Sulphuris. 
Symbol,  K  Ss. 

Fuse  together,  at  a  low  red  heat,  one  part  of  sulphur,  and 
two  of  carbonate  of  potash,  as  long  as  effervescence  takes 
place  ;  then  pour  on  to  a  marble  slab,  and  when  cool,  break 
up  the  mass,  and  keep  it  in  well-closed  bottles.  This  sul- 
phide has  a  liver-brown  appearance.  By  the  addition  of  an 
acid  to  a  solution  of  the  sulphide,  hydrosulphuric  acid  is  lib- 
erated, a  soluble  salt  formed,  and  sulphur  precipitated  of  a 
milk-white  color.  The  alkaline  sulphides  have  the  same  re- 
action on  metallic  salts  as  hydrosulphuric  acid,  forming  pre- 
cipitates of  different  colors,  by  which  frequently  the  metals 
can  be  recognized,  as,  for  instance,  antimony,  cadmium,  etc. 

Preparation  of  Sulphide  of  Ammonium. 
Symbol,  NH4S.HS. 
Let  a  current  of  hydrosulphuric  acid  pass  through  concen- 
trated ammonia  to  saturation  ;  then  add  an  equal  bulk  of 
ammonia.  This  is  one  of  the  most  important  reagents  in 
chemistry.  Hydrosulphuric  acid  produces  precipitates  in 
metallic  salts,  some  of  which  are  soluble  in  sulphide  of  am- 
monium, and  others  not ;  from  this  fact  we  can  distinguish 


126 


INTENSIFIED. 


one  metal  from  another,  thus  the  sulphide  of  arsenic  is  yel- 
low, and  so  is  that  of  cadmium ;  but  the  former  is  soluble  in 
sulphide  of  ammonium,  the  latter  is  insoluble.  The  alkaline 
sulphides  precipitate  silver  black  from  its  solutions ;  thus 
nitrate  of  silver,  as  a  dye  for  the  hair,  is  turned  of  an  intense 
black,  if  followed  up  with  sulphide  of  ammonium. 


CHAPTER  XIX. 

WET  COLLODION  PROCESS. 

If  the  collodionized  plate,  after  sensitization  in  the  silver  * 
bath,  is  exposed  whilst  still  moist,  the  process  by  which  the 
image  is  obtained,  is  called  the  Wet  Collodion  process ; 
whereas  if  the  sensitized  plates  are  dried,  and  used  after- 
ward at  any  indefinite  time,  the  process  of  the  operation  is 
denominated  the  Dry  Collodion  process.  The  Wet  Collo- 
dion process  will  form  the  subject  of  the  following  chapters. 
This  process  is  divisible  into  two  branches,  comprehending 
the  methods  of  preparing  collodion  positives  and  collodion 
negatives. 

Collodion  Positives  —  Tlie  Melainotype — The  Ambrotype. 

A  collodion  positive  may  be  viewed  either  by  reflected 
light  or  transmitted  light ;  by  reflected  light,  in  the  same 
manner  as  any  picture  or  engraving  is  beheld,  that  is,  by 
looking  at  it ;  and  by  transmitted  light,  when  the  picture  is 
seen  in  or  on  glass,  by  looking  through  it,  such  as  the  picto- 
rial representation  on  stained  glass,  or  altar-pieces,  etc. 
Collodion  positive  pictures,  or  portraits  on  glass,  when  re- 
garded by  reflected  light,  are  denominated  ambrotypes. 
Every  part  of  such  a  picture  is  laterally  inverted ;  it  does  not 
therefore  represent  nature  as  it  is.  For  portraits  this  inver- 
sion of  the  left  side  for  the  right  side  is  of  no  great  conse- 
quence, excepting  in  the  representation  of  objects  in  action, 
such  as  a  sportsman  firing  at  a  woodcock,  a  soldier  parry- 
ing off  the  blows  of  an  antagonist,  or  a  lady  sewing,  etc.,  in 
all  which  cases  the  fowling-piece,-  the  sword,  and  the  needle 
will  be  exhibited  in  the  left  hand,  or  on  the  left  side.  The 
artist,  therefore,  has  to  rectify  his  model  in  such  a  way  that 
he  holds,  when  posed,  all  these  accessories  in  an  inverted  or- 
der. Landscapes,  houses,  churches,  etc.,  can  not  be  properly 
represented  in  an  ambrotype  directly  photographed  from  the 
objects ;  the  application  of  collodion  positives,  therefore,  is 
limited  to  portraiture. 


128 


WET  COLLODION  PROCESS. 


Ambrotype. 

There  are  several  things  which  the  photographer  must 
possess,  and  several  arrangements  to  be  made  before  he  can 
take  an  ambrotype.  He  must  have  a  glass-house,  or  operat- 
ing room,  of  course,  with  all  its  accoutrements ;  glass,  collo- 
dion, developer,  and  fixer  must  all  be  ready,  and  in  their 
proper  places,  as  already  described ;  the  sensitizing  bath, 
plate-holders,  water-tanks,  etc.,  all  adjusted. 

The  operation  of  taking  a  collodion  positive  on  glass  con- 
sists of  the  following  subdivisions  : 

First.  Preparing  the  glass. 
Second.  Coating  it  with  collodion. 
Third.  Sensitizing  it. 
Fourth.  Exposing  it  in  the  camera. 
Fifth.  Developing  the  picture. 
Sixth.  Fixing  the  image. 

First  Subdivision. — Preparing  the  Glass. 
Glass  suitable  for  the  photograj)her  must  be  free  from 
flaws  on  the  surface  or  in  the  mass,  flat,  and  quite  transpar- 
ent. It  can  be  procured  already  cut  for  the  various  sizes 
required  ;  or  the  photographer  can  cut  it  himself  from  plates 
of  the  proper  quality.  There  is  quite  a  knack  to  cut  with  a 
diamond  ;  the  line  made  by  a  diamond  on  glass  is  like  the  cut 
made  with  a  sharp  razor  on  a  piece  of  soft  wood  ;  it  is  by  no 
means  a  scratch.  A  diamond  is  wedge-shaped,  and  its  edge 
not  a  straight  line,  but  a  curved  line,  something  like  the  edge 
of  a  cook's  chopping-knife  ;  the  edge  first  makes  an  incision, 
and  the  wedge  splits  its  way  as  the  diamond  proceeds.  The 
position  of  the  edge  has  to  be  found  out,  and  the  diamond 
studied,  before  you  can  cut  with  it,  and  not  scratch  with  it. 
If  you  are  determined  to  cut  your  own  glass,  prepare  a  gla- 
zier's board  and  a  ruler  for  this  purpose,  and  mark  off  with 
marks  the  different-sized  glasses  used  in  the  art,  as  one  ninth, 
one  sixth,  one  fourth,  one  half,  four  fourths,  and  steresocopic, 
etc.,  plates. 

Next  see  that  your  glasses,  so  far  cut,  are  of  a  right  size 
for  your  plate-holders  ;  for  it  is  very  annoying  when  the  film 
is  sensitized  to  find  that  the  plate  is  either  too  big  or  too 
small  for  the  holder.    Never  omit  this  precaution. 

The  next  duty  is  to  take  the  glass  in  the  left  hand,  and 
with  the  right  hand  to  run  a  file  along  each  edge  of  the  cut 
glass,  beginning  at  the  left-hand  corner,  and  proceeding  to 
the  right-hand  corner  all  the  way  round ;  the  glass  is  then 


WET  COLLODION  PROCESS. 


129 


turned  round  to  the  other  side,  and  its  edges  are  treated  in 
the  same  manner.  The  object  in  view,  by  thus  abrading  the 
edges,  is  firstly  to  take  precautions  against  the  cutting  pro- 
perties of  such  sharp  edges ;  and  secondly,  it  is  found  that 
the  collodion  film  adheres  better  to  the  edges  of  the  glass 
when  it  is  so  prepared. 

If  you  are  provided  with  a  patent  vice,  placed  right  in  front 
of  you  in  an  appropriate  place,  on  the  table  or  bench  in  the 
operating  room,  (and  such  a  vice  is  a  very  useful  accessory,) 
the  plate  is  fixed  in  this  horizontally.  Now  take  the  bottle 
containing  prepared  rotten-stone,  covered  at  the  wide-mouthed 
orifice  with  a  piece  of  gauze,  instead  of  being  closed  with  a 
cork,  and  dust  a  small  quantity  of  rotten-stone  upon  the  (ten- 
ter of  the  plate  ;  then  drop  upon  the  rotten-stone  on  the  plate 
from  ten  to  twenty  drops  of  alcohol,  and  with  a  piece  of  Canton 
flannel,  rub  the  mixture  about  from  side  to  side,  and  in  the 
center  until  the  surface  of  the  glass  is  perfectly  clean.  A 
clean  piece  of  the  flannel  is  then  used  to  remove  all  the  re- 
maining particles  of  rotten-stone,  after  which  the  plate  of 
glass  is  seized  with  a  silk  handkerchief,  so  that  the  fingers 
do  not  come  in  contact  with  the  glass,  which  is  turned  round, 
clamped,  and  its  surface  is  cleaned  in  like  manner.  Both 
sides  being  now  apparently  clean,  again  seize  the  plate  with 
a  clean  silk  handkerchief  in  the  left  hand,  remove  it  from  the 
vice,  and,  holding  a  clean  silk  cloth  in  the  right  hand,  go 
round  the  edges,  remove  all  dust  from  them,  and  from 
either  side,  then  breathe  upon  either  side ;  if  the  breath 
forms  a  uniform  film,  and  vanishes  uniformly  without  any 
irregularity,  the  surfaces  are  cleaned.  By  this  system  of 
friction  the  glass  becomes  electrified,  and  small  fibers  of  cot- 
ton or  silk  and  small  particles  of  dust  are  very  apt  to  be  at- 
tracted to  the  surface ;  these  must  be  removed  by  a  flat  sable 
or  camel's  hair  pencil.  The  plate  is  now  ready  for  the  sec- 
ond operation. 

Second  Subdivisio?i. 

Holding  the  plate  horizontally  by  the  smallest  portion 
possible  of  the  left-hand  corner,  between  the  thumb  and  the 
first  finger  of  the  left  hand,  pour  over  its  surface,  beginning 
at  the  right-hand  corner,  a  sufficient  quantity  of  collodion  to 
cover  it ;  when  it  is  supposed  that  there  is  sufficient  collo- 
dion poured  out,  lower  the  nearest  edge  and  the  nearest 
right-hand  corner,  so  that  the  collodion  can,  by  the  inclina- 
tion of  the  plate,  be  made  to  flow  uniformly  over  the  sur- 
face, and  its  superfluous  quantity  can  be  drained  into  the 
6* 


130 


WET  COLLODION  PEOCESS. 


collodion  bottle.  A  wide-mouthed  bottle  containing  a  couple 
of  ounces  will  be  found  to  be  an  appropriate  shaped  vessel 
to  contain  the  collodion  for  present  use  when  the  pictures 
are  small.  Collodion  is  apt  to  indurate  around  the  orifice 
of  the  bottle  ;  and  if  this  dry  film  is  not  carefully  removed 
every  time,  it  may  cause  trouble  by  flowing  off  in  fragments 
along  with  the  collodion,  and  thus  spoil  the  collodion  film. 
This  trouble  is  obviated  in  a  great  measure  by  the  use  of 
what  are  denominated  "  cometless  vials ;"  they  are  made 
for  this  special  purpose.  If  the  collodion  is  thick  and  glutin- 
ous, it  will  be  no  easy  matter  to  obtain  a  film  on  the  glass 
free  from  ridges.  In  such  a  case  an  additional  quantity  of 
alcohol  generally  renders  the  collodion  thinner,  less  glutin- 
ous, and  more  structureless.  Supposing  the  film  to  be  even, 
free  from  ridges,  from  wooliness,  and  specks  of  every  kind, 
allow  every  drop  of  the  collodion  to  drain  off,  then  wait  until 
it  has  set,  which  will  be  effected  in  a  very  short  time.  It  is 
very  easy  to  ascertain  by  a  touch  of  the  finger  on  the  right- 
hand  corner,  whether  the  film  is  sufficiently  dry  or  not ;  if  it 
no  longer  yields  beneath  a  slight  touch,  the  plate  is  ready 
for  the  next  step.  By  the  way,  I  may  here  remark,  that  it  is 
by  far  the  most  advisable  plan  for  a  practical  photographer 
not  to  manufacture  his  collodion ;  unless  he  be  in  some  de- 
gree a  chemist,  acquainted  with  the  neatness  and  accuracy 
of  chemical  manipulations,  and  have  plenty  of  leisure  time 
as  an  amateur,  he  can  seldom  succeed  in  preparing  at  all 
times  when  required  a  reliable  specimen  of  collodion  ;  and 
to  prepare  small  quantities  of  collodion,  as  well  as  of  any 
other  chemical  compound,  seldom  comports  itself  with  econo- 
my. Beside  this,  there  is  no  necessity  for  such  a  sacrifice  of 
time  and  economy  in  a  country  like  this,  where  collodion  can 
be  purchased  of  so  superior  a  quality  for  all  the  ordinary 
operations  of  the  practical  photographer.  Only  observe  this 
rule,  make  your  purchases  at  first-class  houses  in  large  cities, 
who  make  it  their  sole  business  to  supply  unadulterated  ma- 
terials. 

Third  Subdivision. 

When  the  film  has  indurated  place  it  upon  the  ledge  of 
the  dipper  and  lower  it  in  one  continuous  and  rather  quick 
motion  into  the  sensitizing  bath.  Take  care  that  no  actinic 
rays  get  to  the  bath  during  this  operation.  After  three  or 
four  minutes  raise  the  dipper  a  moment  and  examine  the 
collodionized  plate ;  if  the  film  is  still  bluish,  and  as  if  covered 
with  streaks  or  specks  of  oil,  lower  it  again  and  let  it  remain 


WET  COLLODION  PEOCESS. 


131 


until  the  collodion  has  a  yellowish-white  creamy  appearance, 
and  is  free  from  all  oiliness.  Withdraw  it  from  the  bath, 
seize  the  right-hand  corner  between  the  thumb  and  finger 
of  the  right  hand  ;  allow  the  silver  solution  to  drain  off*  thor- 
oughly into  the  bath  ;  with  a  piece  of  blotting-paper  remove 
all  specks  of  collodion  from  the  back  of  the  plate,  taking 
care  not  to  disturb  the  collodion  along  the  edges  of  the  plate 
or  on  the  film  side ;  remove  the  last  drop  of  silver  from  the 
lowest  corner,  place  it  in  the  plate-holder,  and  close  the  slide 
and  the  shutter.  Previous  to  this,  the  camera  is  supposed  to 
have  been  fixed  before  the  sitter,  and  the  picture  accurately 
focussed.  It  is  supposed,  moreover,  that  the  surface  of  the 
ground-glass  and  the  collodion  film  are  exactly  at  an  equal 
distance,  when  placed  in  the  groove,  from  the  back  lens. 
As  before  observed,  unless  the  picture  is  correct  on  the 
ground-glass,  free  from  all  haze,  bright,  sharp,  and  the  light 
uniformly  subdued,  it  will  be  very  unlikely  that  the  collo- 
dion picture  will  be  a  successful  one  ;  in  fine,  the  image  on 
the  film  will  never  be  better  than  the  one  on  the  ground- 
glass  where  the  lens  has  been  accurately  adjusted ;  and 
furthermore,  that  if  the  picture  on  the  ground-glass  be  clear, 
sharp,  distinct,  and  agreeably  contrasted  with  light  and 
shade,  you  are  legitimately  authorized  to  expect  a  similar 
favorable  result  on  the  collodion.  Be  careful,  therefore,  in 
bringing  every  part  of  the  model  into  as  accurate  a  focus  as 
possible — be  careful  in  the  management  of  the  light. 

Fourth  Subdivision. 
Place  the  cap  on  the  lens  ;  let  the  eye  of  the  sitter  be  di- 
rected to  a  given  point ;  withdraw  the  ground-glass  slide  ; 
insert  the  plate-holder  ;  raise  or  remove  its  slide  ;  Attention ! 
One,  two,  three,  four,  five,  six  !  (slowly  and  deliberately  pro- 
nounced in  as  many  seconds,  either  aloud  or  in  spirit.)  Cover 
the  lens.  Down  with  the  slide  gently  but  with  firmness. 
Withdraw  the  plate-holder  and  yourself  into  the  dark-room, 
and  shut  the  door.    Now  comes  the 

Fifth  Subdivision. 
Placing  the  plate-holder,  still  containing  the  plate,  in  an 
inclined  position  against  the  wall  in  its  regular  and  proper 
position,  open  the  shutter  and  take  out  the  collodion  plate 
carefully,  so  as  not  to  injure  the  film,  by  inserting  the  nail 
of  the  first  finger  along  the  cavity  on  the  upper  part  of  the 
plate-frame,  and  drawing  forward  the  plate  so  as  to  let  it 
fall  into  the  left  hand  ;  the  plate  is  then  seized  by  the  left- 


132 


WET  COLLODION  PROCESS. 


hand  corner  between  the  thumb  and  the  finger.  In  this 
position  the  plate  can  easily  be  covered  with  the  developing 
liuid  in  precisely  the  same  way  as  with  collodion,  only  the 
operation  must  be  much  quicker,  in  order  to  cover  the  sur- 
face without  producing  any  lines  of  stoppage,  which  invaria- 
bly happens  unless  the  plate  be  flowed  all  at  once.  When 
the  plate  is  large,  it  is  preferable  to  take  it  by  the  right-hand 
corner  and  lay  it  in  the  left-hand  corner  of  a  gutta-percha 
dish,  whose  lateral  dimensions  are  about  twice  as  large  as 
those  of  the  plate.  Then,  holding  the  dish  in  the  left  hand, 
incline  the  right  side  downward,  and  pour  into  it  a  quantity 
of  the  developing  fluid.  By  a  quick  motion  the  fluid  can  be 
made  to  cover  the  surface  of  the  plate  in  one  continuous 
flow.  As  soon  as  every  part  is  thus  covered  the  plate  is 
taken  out  with  a  quantity  of  the  solution  upon  it,  and  the 
operation  watched.  By  proceeding  in  this  way  two  diffi- 
culties are  avoided ;  the  first  of  which  consists  in  washing 
away  a  portion  of  the  nitrate  or  iodide  of  silver,  etc.,  on  that 
part  on  which  the  solution  is  allowed  to  fall  if  the  first 
method  be  adopted,  whereby  a  diminution  of  reduction  is 
observable  in  this  part ;  secondly,  you  avoid  the  liability  of 
forming  islands  and  curved  lines  of  demarkation  where  there 
is  the  slightest  stoppage  in  the  flowing  of  the  developer. 
Supposing  the  plate  to  be  covered,  however,  you  then  watch 
proceedings.  If  a  bright  silver-white  film  be  desired,  it  is 
well  to  make  use  of  a  slow  developer,  such  as  is  used  for 
negative  purposes,  containing  in  addition  a  few  drops  of 
nitrate  of  silver,  nitrate  of  potassa,  and  nitric  acid.  Take, 
for  instance,  the  following,  which  is  found  to  work  well  with 
a  white  background,  giving  a  roundness  of  figure  more  like 
that  of  a  daguerreotype. 

Formula  for  Developer. 

Sulphate  of  iron,   2  drachms. 

Rain-water,   8  ounces. 

Acetic  acid,  ........    2  drachms. 

Alcohol,   1  drachm. 

Nitrate  of  potassa,   \  drachm. 

Nitrate  of  silver  solution,  ...  30  drops. 

Nitric  acid,   12  drops. 

The  image  will  gradually  appear,  and  if  the  time  of  ex- 
posure has  been  right,  you  will  be  able  to  observe  the  three 
grades  of  contrast  in  the  development,  that  is,  dark  parts  or 
shades,  middle  tones,  and  lights.  You  will  see,  moreover, 
whether  the  relative  conditions  of  the  collodion  and  the 
silver-bath  are  in  good  working  order,  by  the  mode  in  which 


WET  COLLODION  PROCESS. 


133 


the  development  takes  place.  If  the  whole  surface  of  the 
collodion  plate  soon  assumes  a  foggy,  milky,  or  clouded  ap- 
pearance, with  but  faint  contrast  between  the  lights  and 
shades,  (and  knowing  that  the  camera  is  quite  impermeable 
to  light  excepting  through  the  lens,)  you  may  fairly  con- 
clude one  of  two  things,  either  that  the  time  of  exposure 
was  too  long,  or  the  condition  of  the  materials  was  not 
normally  good.  Of  these  difficulties  I  will  speak  shortly. 
By  carefully  watching  the  development  it  is  not  difficult  to 
observe  how  the  shades  increase  in  density,  how,  in  fine,  the 
picture  becomes  more  and  more  developed ;  and  particularly 
the  photographer  can  distinguish  the  regular  shading  of  the 
background.  At  last  the  development  arrives  at  its  culmin- 
ating point ;  if  it  were  to  proceed  any  further,  the  back- 
ground and  the  transparent  parts  would  begin  to  be  foggy ; 
the  contrast  diminishes,  and  finally  the  picture  is  spoiled. 
The  rule  is  this  :  the  moment  the  image  is  complete  and  the 
background  has  received  its  first  shade,  pour  off  the  remain- 
ing part  of  the  developer,  and  wash  immediately  and  thor- 
oughly by  allowing  a  small  stream  of  rain-water  to  play  upon 
the  surface  until  every  trace  of  the  iron  is  removed.  Wash 
also  the  posterior  side  of  the  glass  in  like  manner.  We  now 
proceed  to  the  sixth  and  last  operation. 

Sixth  Subdivision. — Fixing  Solution. 
Formula. 

Cyanide  of  potassium,  ....  1  drachm. 
Rain-water,  4  ounces. 

Have  this  solution  ready.  With  the  right  hand  place  the 
collodionized  plate  in  a  gutta-percha  dish  held  in  the  left 
hand,  and  pour  upon  the  developed  image  a  quantity  of  the 
above  solution  in  a  gentle  stream,  until  all  the  white  or  yel- 
low iodide  of  silver  has  been  completely  dissolved,  taking 
care  in  the  mean  while  that  the  fluid  is  kept  moving  back- 
ward and  forward,  so  as  to  preserve  uniformity  of  action. 
After  this  operation  wash  the  plate  again  in  many  waters  on 
both  sides  and  until  all  traces  of  the  cyanide  are  removed. 
Holding  the  positive  now  over  a  piece  of  black  velvet  in 
such  a  position  by  a  window  that  the  impingent  rays  shall 
reach  the  eye,  the  quality  of  the  ambrotype  can  be  deter- 
mined. The  picture  must  be  quite  clear ;  the  shades  dark, 
almost  black  ;  the  lights  brilliant  and  white  ;  and  in  every 
respect  the  lines  and  points  must  be  sharply  defined.  If 
there  is  no  regular  gradation  of  light  into  shade,  bat  almost 
one  mass  of  shade,  and  the  picture  is  olfensively  black,  the 


134 


WET  COLLODION  PROCESS. 


time  of  exposure  was  too  short  or  the  development  not  car- 
ried on  far  enough  ;  but  if  in  this  case  the  development  had 
been  continued  until  the  retrograde  action  had  set  in,  then 
certainly  the  time  was  too  short.  The  remedy  in  such  a  case 
is  quite  natural ;  rub  the  picture  out  and  take  another  with 
a  longer  exposure.  If,  on  the  contrary,  the  picture  is  hazy, 
or  foggy  as  it  is  technically  denominated,  and  the  lights  and 
shades  too  much  blended  or  too  little  distinct  from  each 
other,  and  the  development  was  rapid,  and  a  difficulty  pre- 
sented itself  in  discriminating  when  the  reduction  began  to 
assume  a  retrograde  action,  in  such  a  case  it  may  be  confi- 
dently concluded  that  the  time  of  exposure  was  too  long. 
The  remedy  of  course  is  known.  But  the  defects  just  men- 
tioned might  have  been  caused  by  carrying  on  the  develop- 
ment too  long ;  and  it  would  be  very  proper  to  attribute 
these  defects  to  this  cause,  if  the  development  had  been  slow 
and  carelessly  watched.  But  if  the  haze  and  fogginess  com- 
menced almost  as  soon  as  the  developing  solution  was  poured 
upon  the  surface,  you  would  be  justified  in  ascribing  the 
cause  of  this  veil  over  the  picture  to  an  abnormal  condition 
of  the  silver-bath  or  the  collodion.  This  evil  indicates,  as  a 
general  thing,  alkalinity  in  either  one  or  the  other,  or  in 
both,  and  can  be  remedied  by  rendering  either  one  or  the 
other  acid.  It  may  be  caused  by  a  new  bath  and  a  new 
neutral  silver  solution. 

Remedy  for  Fogginess. 
If  the  collodion  is  nearly  colorless  and  new,  this  material 
is  probably  the  cause  of  the  want  of  contrast  in  the  picture, 
of  the  feebleness  in  the  development,  and,  it  is  possible,  of 
the  veil  that  covers  the  whole  plate.  Take  some  highly 
colored  old  collodion  and  add  it  to  the  new  in  the  propor- 
tion of  one  drachm  in  ten,  and  try  another  picture ;  or  add 
to  the  collodion  tincture  of  iodine,  that  is,  a  solution  of 
iodine  in  alcohol.  In  either  case,  most  likely,  under  the  cir- 
cumstances, an  improvement  will  be  manifest.  If  the  pic- 
ture is  not  yet  perfectly  clear,  proceed  in  the  same  direction, 
that  is,  add  more  of  the  old  collodion  or  of  the  tincture.  If 
the  bath  is  quite  neutral  or  alkaline,  it  will  be  well  indeed  to 
drop  in  a  minim  or  two  of  nitric  acid.  To  do  this  take  a 
drachm  of  distilled  water  and  drop  into  it  five  minims  of 
nitric  acid.  The  mixture  contains  about  sixty  drops,  of 
which  six  drops  will  contain  about  half  a  drop  of  nitric  acid. 
Begin,  therefore,  and  add  six  drops  of  the  solution  to  the 
bath,  and  keep  doing  so  until  the  picture  is  perfectly  satis- 


WET  COLLODION  PROCESS. 


135 


factory.  I  prefer  myself  keeping  the  bath  as  nearly  neutral 
as  possible,  and  to  apply  the  remedial  action  to  the  collodion, 
by  adding  free  iodine  or  old  collodion,  of  which  the  former 
seems  by  decomposition  to  liberate  an  acid  in  and  on  the 
collodion  film  in  proper  quantity,  at  the  right  time,  and  in 
the  proper  place ;  and  the  latter,  that  is,  old  collodion,  effects 
the  same  result,  because  it  has  already  undergone  the  de- 
composition of  the  pyroxyline  that  is  called  ripening,  and 
contains  the  materials  for  producing  intensity  and  for  avoid- 
ing fogginess. 

•In  taking  collodion  positives  beginners  are  very  apt  to  de- 
velop the  plate  too  long,  as  well  as  frequently  to  expose  in 
the  camera  too  long.  The  right  time  in  both  instances  can 
be  attained  only  by  practice,  after  having  consulted  the  best 
instructions.  As  soon  as  the  picture  is  distinctly  visible  by 
reflection,  stop  the  development ;  if  it  is  then  faulty,  the  time 
was  either  too  long  or  too  short ;  too  short,  if  the  shades  are 
altogether  too  black,  and  transparent  by  transmitted  light, 
and  vice  versa,  if  the  reverse. 

Supposing  the  picture  to  be  correct  and  satisfactory,  we 
proceed  next  to  the 

Seventh  Operation, 

which  consists  in  drying  the  plate.  The  operation  is  per- 
formed by  means  of  the  large  flame  of  an  alcohol  lamp,  or 
by  the  radiating  heat  from  a  stove.  Holding  the  plate  by 
the  left-hand  corner,  between  the  finger  and  the  thumb  of 
the  left  hand,  first  allow  all  the  water  to  drain  off  at  the 
nearest  right-hand  corner,  by  inclining  the  plate  for  this 
purpose ;  then  holding  the  lamp  in  the  right  hand,  move  the 
flame  gently  over  the  back  of  the  plate,  so  as  to  avoid  frac- 
ture, beginning  at  the  top  and  proceeding  from  side  to  side, 
and  gradually  downward,  until  the  film  is  thoroughly  dried. 
A  second  inspection  now,  by  viewing  the  picture,  as  before, 
on  a  dark  background,  and  by  reflected  light,  decides  whether 
the  positive  is  good,  tolerable,  or  indifferent,  because  now 
the  final  colors  of  the  shaded  parts  are  attained.  These 
shaded  parts  are  of  a  bright,  white  silvery  hue,  with  the  de- 
veloper above  given.  Some  tastes  are  more  gratified  with 
a  more  subdued  contrast  in  which  the  whites  are  more  dead- 
ened. This  can  be  effected  by  making  use  of  a  much  more 
rapid  developer,  and  by  omitting  the  nitrate  of  silver,  and 
the  nitric  acid.  For  this  purpose  the  following  formula  will 
be  found  practicable. 


< 


136 


WET  COLLODION  PROCESS. 


Formula  No.  2.    For  Collodion  Positives. 

Sulphate  of  the  protoxide  of  iron,     4  drachms. 

Acetic  acid,  6  drachms. 

Water,  8  ounces. 

Alcohol,  2  ounces. 

Nitrate  of  baryta,  2  drachms. 

Mix  intimately,  and  filter  before  using.  Prepare  fresh 
every  clay. 

Eighth  Operation. 

The  next  step  which  the  artist  has  to  take  consists  in  re- 
moving any  particles  that  may  have  settled  upon  the  surface 
of  the  picture,  and  in  coloring  the  cheeks,  hands,  and  dra- 
pery where  required.  Dry  colors  are  used ;  those  of  New- 
man are  regarded  as  the  best.  Very  little  color  will  produce 
an  agreeable  effect.  With  a  fine  sable  or  fitch  pencil,  take 
a  small  portion,  and  rub  it  gently  on  either  cheek,  on  the 
lips,  the  hands,  and  forehead ;  then  brush  off  the  extraneous 
quantity,  or  shade  the  color  off  from  the  center  of  the  cheeks, 
for  instance,  to  the  edges.  On  the  lights  of  the  drapery  the 
requisite  coloring  may  be  laid  on  in  like  manner.  This  op- 
eration of  coloring  is  frequently  performed  on  the  varnished 
surface.  Finally  with  a  large  broad  sable  pencil  remove  all 
loose  coloring  particles,  and  now  the  positive  is  ready  for  the 

Ninth  Operation. 

Whilst  the  plate  is  still  warm,  uniformly  warm  from  the 
drying  operation,  flow  it  with  the  purest  and  most  transpar- 
ent crystal  varnish,  precisely  in  the  same  manner  as  the 
plate  was  covered  with  collodion.  The  operation  must  be 
performed  with  dexterity  and  care ;  with  dexterity  in  order 
to  avoid  all  ridges  caused  by  stoppage,  and  with  care  to 
avoid  loss  of  varnish  by  escaping  to  the  posterior  part  of 
the  plate,  upon  the  fingers,  and  upon  the  sides  of  the  bottle, 
and  the  floor.  The  indurated  varnish  on  the  back  of  the  pos- 
itive may  be  removed  by  a  tuft  of  cotton  wool,  dipped  either 
in  alcohol,  benzole,  or  chloroform,  according  as  the  resins  in 
the  varnish  are  dissolved  in  either  of  these  menstrua.  '  Do 
not  apply  any  heat  from  a  large  flame  on  the  back  of  the 
plate  before  the  varnish  has  dried,  otherwise  the  ethereal 
fluid  in  which  it  is  dissolved  will  take  fire  in  many  instan- 
ces, and  spoil  the  varnished  surface.  When  the  film  is  some- 
what dry  and  indurated,  and  not  quite  smooth,  heat  may  be 
applied  carefully,  in  order  to  remove  the  unevenness,  or  the 
want  of  brilliancy. 


WET  COLLODION  PROCESS. 


137 


Varnishes  for  Collodion  Pictures. 
Formula  No.  1. 

Copal,  1  ounce. 

Pure  benzole,   15  ounces. 

Dissolve  and  filter  through  Swedish  or  ordinary  .filtering 
paper. 

Formula  No.  2. 

White  stick  lac,  3  ounces. 

Picked  sandarac,  3  drachms. 

Alcohol,  spec,  grav.,  .815,  .    .    .    40  ounces. 
Oil  of  bergarupt,  6  drops. 

Dissolve  the  resins  in  the  alcohol  by  means  of  a  water-bath, 
and  filter.  This  varnish  is  immediately  ready  for  use  ;  and, 
like  all  varnishes,  is  the  best  when  new. 

Formula  No.  3.    Crystal  Varnish.    Soft  Copal  Varnish. 
Finely  powdered  Dammar  resin,  .      5  ounces. 
Benzole,  50  ounces. 

Set  aside  in  a  closed  vessel  for  a  week,  shaking  the  mixture 
from  time  to  time  for  a  day  or  two  ;  then  allow  the  insoluble 
gum  to  subside.  Draw  olF  the  supernatant  liquid,  which, 
when  clear,  is  ready  for  use.  The  collodion  plate  must  be 
quite  dry  and  cold  when  this  varnish  is  applied,  and  the  lat- 
ter is  allowed  to  dry  spontaneously. 

Formula  No.  4.    Amoer  Varnish,  (with  Chloroform.) 
Amber  in  fine  powder,    ....      3  ounces. 
Chloroform,  50  ounces. 

Shake  the  mixture  from  time  to  time  for  eight  or  ten  days, 
and  then  filter.  This  varnish,  like  the  preceding,  is  poured, 
like  collodion,  upon  the  cold  plate,  but  with  great  dexterity, 
because  it  dries  very  rapidly. 

Formula  No.  5.    Amoer  Varnish,  (with  Benzole.) 

Amber,  3  ounces. 

Benzole,   50  ounces. 

Heat  the  amber  first  in  a  close  vessel  to  a  temperature  of 
about  570°  Fahr.,  when  it  begins  to  soften  and  swell,  yielding 
white  fumes.  It  is  then  dissolved  in  the  benzole.  This  var- 
nish too  is  flowed  upon  the  cold  plate,  and  allowed  to  dry 
spontaneously.  These  two  varnishes  are  more  especially 
adapted  for  negatives. 

If  it  should  happen  that  a  collodion  picture  becomes  some- 
what spoiled  by  the  cracking  of  the  varnish,  it  is  recommend- 
ed, if  its  restoration  or  preservation  be  of  great  importance, 
to  take  the  following  method.    First  ascertain  whether  the 


138 


WET  COLLODION  PROCESS. 


solvent  of  the  varnish  on  the  plate  be  alcohol,  chloroform,  or 
benzole,  by  dropping  on  one  corner  a  minute  drop  of  each  of 
these  menstrua,  to  ascertain  which  dissolves  the  varnish. 
Next  take  a  tin  box,  somewhat  larger  than  the  picture,  about 
one  inch  deep.  At  the  bottom  of  this  box  solder  a  ring  of 
tin,  about  half  an  inch  wide,  of  the  same  shape,  and  nearly 
of  the  same  size,  as  a  support  for  the  glass  plate.  Pour  a 
small  quantity  of  the  solvent  on  the  outside  of  the  support ; 
place  the  plate  collodion-side  upward  on  the  ring ;  cover 
the  box  as  nearly  air-tight  as  possible  with  a  piece  of  glass, 
and  place  it  in  a  water  bath.  The  vapor  of  the  solvent  will 
soon  cause  the  varnish  to  swell,  and  the  edges  of  the  cracks 
to  coalesce.  As  soon  as  this  end  in  view  is  accomplished,  the 
plate  is  carefully  withdrawn,  and,  when  cool,  is  again  var- 
nished with  a  similar  varnish. 

The  plate  having  been  varnished  with  a  transparent  resin 
varnish,  we  proceed  finally  to  the  last  operation. 

Tenth  Operation. 
We  have  now  to  make  a  background  for  the  positive,  of 
some  black  material,  which  may  consist  of  a  piece  of  black 
velvet,  black  paper,  etc.,  of  the  same  size  as  the  plate ;  or  we 
may  apply  a  coating  of  black  varnish,  either  to  the  collodion 
surface,  or  to  the  posterior  surface  of  the  glass.  If  the  var- 
nish on  the  background  be  applied  to  the  collodion  side,  the 
picture  is  not  laterally  inverted,  but  it  loses  considerably  in 
transparency  by  the  intervening  collodion ;  in  consequence 
of  this  inconvenience,  the  background  is  generally  placed  on 
the  side  of  the  glass  without  the  collodion. 

Formula  JSTo.  1.    For  Black  Varnish. 

Oil  of  turpentine,  50  ounces. 

Asplialtum,  2  ounces. 

Canada  balsam,  4  ounces. 

Formula  N'o.  2.    For  Black  Varnish. 

Benzole  or  coal-tar  naphtha,    .    .    50  ounces. 

Asphaltum,  2  ouuces. 

India-rubber,   -J  drachm. 

Formula  JSfo.  3.    For  Black  Varnish. 

Camphene,  50  ounces. 

Pulverized  bitumen,  10  ounces. 

White  wax,   2  ounces. 

Lampblack,  1  ounce. 

Mix  these  ingredients  together,  and  dissolve  by  a  gentlo 
heat ;  afterward  filter  and  preserve  in  a  well-corked  bottle. 


WET  COLLODION"  PROCESS. 


139 


Vamisli  with  oleached  Shell-lac. 
Formula. 

Freshly  bleached  shell-lac,     ...    4  ounces. 

Alcohol,  1  quart. 

Camphor,  2  drachms. 

Canada  balsam,  2  drachms. 

Dissolve  at  a  warm  temperature ;  allow  to  settle,  and  decant 
the  clear  portion  for  use. 

Formula. 

The  following  varnish  is  used  on  the  cold  plate,  is  very 
hard  when  dry,  and  is  not  softened  at  a  high  t&nperature 
when  printing. 

Gum  sandarac,  4  ounces. 

Oil  of  lavender,  3  ounces. 

Alcohol,  28  ounces. 

Chloroform,  5  drachms. 

Digest,  dissolve,  and  decant  as  usual. 

The  positive  print,  denominated  an  ambrotype,  is  now  fin- 
ished. It  remains  only  to  fix  it  in  a  case  or  frame.  In  the 
first  place  a  piece  of  very  transparent  and  unblemished  glass, 
of  the  same  size  as  the  type,  is  thoroughly  cleaned,  and  its 
edges  filed,  as  for  collodion  purposes,  and  all  particles  are 
brushed  from  its  surface.  It  is  then  placed  in  a  Preserver  ; 
over  this  comes  a  Mat ;  next  the  Ambrotype.  The  two  lat- 
ter are  then  firmly  folded  within  the  flexible  edges  of  the 
preserver,  and  the  compact  mass  is  finally  adjusted  in  its  ap- 
propriate case. 


CHAPTER  XX. 


ALABASTRINE  POSITIVES. 

The  cojoring  of  collodion  positives,  as  already  remarked, 
may  be  effected  on  the  whites  of  the  picture,  either  before 
the  varnish  is  flowed  on,  or  upon  the  varnish  itself.  When  well 
performed,  it  communicates  life  and  roundness  to  a  picture 
which  before  was  flat  and  lifeless.  The  colors  in  use  are  in 
fine  powder,  and  are  laid  on  with  a  dry  and  very  fine  pencil 
of  camel's,  etc.,  hair.  Naturally  the  operation  must  be  very 
simple,  and  but  a  very  small  quantity  of  color  must  be  used, 
otherwise  the  operation  will  become  a  work  of  art,  and  none 
but  an  artist  could  perform  it.  In  all  ordinary  cases  the 
color  lies  on  the  surface,  and  does  not  penetrate  into  the  ma- 
terial of  the  film.  In  the  Alabastrine  process,  however,  the 
film  is  so  treated  as  to  become  permeable  to  varnish,  and  thus 
to  exhibit  the  color,  as  it  were,  in  the  collodion ;  besides  this 
the  whites  are  still  retained  white,  notwithstanding  the  im- 
pregnation of  the  film  with  the  penetrating  varnish.  Posi- 
tives treated  in  this  manner  are  regarded  through  the  glass 
and  the  collodion  film ;  the  pictures,  therefore,  are  direct  as 
they  ought  to  be.  The  mode  by  which  the  tones  are  pre- 
served soft  and  white,  and  rendered  at  the  same  time  per- 
meable, is  the  following : 

Alabastrine  Solution, 
Formula. 

Sulphate  of  the  protoxide  of  iron,  .    20  grains. 

Bichloride  of  mercury,  40  grains. 

Chloride  of  sodium,  (salt,)  ...  15  grains. 
Rain-water,  2  ounces. 

Select  for  this  operation  a  vigorous  good  positive  ;  a  faint 
and  thin  film  does  not  answer  well.  One  that  has  been  ra- 
ther under-exposed  is  most  suitable.  Then,  whilst  the  collo- 
dion film  is  still  moist  from  fixing,  pour  upon  it  a  quantity 
of  the  above  solution,  and  keep  it  in  motion.  At  first  the 
picture  assumes  a  dead  and  gray  appearance ;  but  this  soon 
changes,  and  becomes  continually  more  and  more  brilliant. 


ALABASTRINE  POSITIVES. 


141 


It  is  sometimes  necessary  to  add  a  little  more  of  the  fresh 
solution,  and  to  retain  this  solution  on  the  surface  until  the 
whites  are  perfectly  clear.  The  time  required  for  this  oper- 
ation varies  according  to  the  temperature  and  the  thickness 
of  the  film.  Heat  promotes  the  effect ;  the  plate  is  therefore 
frequently  supported  on  the  ring  of  a  retort-stand,  with  the 
fluid  on  its  surface,  whilst  a  small  flame  is  kept  in  motion 
beneath  it.  Unless  this  precaution  be  observed,  there  will 
be  a  liability  to  break  the  plate.  It  happens  sometimes  that 
a  few  minutes  are  sufficient ;  but  generally  more  time  is  re- 
quired. If  no  heat  is  applied,  the  operation  may  require  in 
some  cases  as  much  as  an  hour.  As  soon  as  the  whites  have 
attained  their  utmost  purity,  the  operation  is  complete.  It 
is  better  to  be  quite  certain  that  the  whites  have  attained  the 
purity  required,  than  to  shorten  the  time,  and  have  the  ef- 
fect underdone.  There  is  no  danger  in  giving  too  much 
time ;  but  it  is  a  disadvantage  to  remove  the  fluid  from  the 
plate  too  soon ;  because  in  drying,  the  whites  in  such  a  case 
are  apt  to  grow  darker  again,  and  the  picture  assumes  then 
the  cold  blue  tone,  which  arises  from  treatment  with  corro- 
sive sublimate  alone. 

As  soon  as  the  effect  has  been  reached,  the  plate  is  tho- 
roughly washed  in  several  waters,  and  then  dried  over  the 
spirit-lamp.  The  plate  is  now  ready  for  the  first  coating  of 
varnish,  which  communicates  transparency  to  the  shadows, 
without  at  all  impairing  the  whites. 

The  next  operation  is  to  lay  on  the  colors  carefully  and  ar- 
tistically on  those  parts  that  require  them.  It  is  unnecessary 
to  apply  any  to  the  shades.  Where  much  color  is  desired  on 
a  given  surface,  it  is  better  to  apply  it  by  repetition,  and  not 
in  one  thick  blotch.  Colors  thus  tastefully  laid  on  produce 
a  very  brilliant  effect,  by  reason  of  the  purity  of  the  whites  ; 
and  this  effect  is  again  increased  by  the  softness  communi- 
cated to  the  whole  picture  by  the  application  of  the  penetrative 
varnish,  which  causes  the  color  to  permeate  into  the  pores  of 
the  film,  or  to  be  seen  at  least  in  full  beauty  from  the  oppo- 
site side.  This  varnish  is  nothing  more  than  a  very  pure 
strong-bodied  protective  varnish.  The  picture  so  far  finish- 
ed is  backed  up  with  a  piece  of  black  velvet,  but  never  with 
black  Japan,  which  would  injure  the  film. 


CHAPTER  XXI. 


MELAINOTYPE  FERROTYPE. 

The  melainotype  takes  its  name  from  the  black  background 
upon  which  it  is  taken.  Ferrotype  from  the  iron  of  which 
it  is  composed.  Very  thin  plates  of  sheet-iron  are  covered 
with  a  protective  varnish  or  Japan,  of  which  one  is  of  a  rich 
black  or  brown-black  color,  highly  polished,  and  without 
flaw,  for  the  reception  of  the  collodion  and  the  collodion  pic- 
ture. Glass  in  this  sort  of  picture  is  entirely  dispensed  with, 
and  so  is  also  the  black  Japan,  the  black  velvet,  and  paper. 
This  type  is  by  far  the  easiest  and  the  quickest  to  take,  and 
in  general  the  most  satisfactory  when  taken.  Melainotype 
plates  of  all  the'variable  photographic  sizes,  and  of  variable 
qualities,  can  be  obtained  from  the  photographic  warehouses. 
The  Excelsior  plate  and  the  Eureka  plate  in  my  opinion  are 
the  best ;  the  Ferrotype  is  very  good,  and  much  cheaper. 

Operation. 

With  a  fine  flat  sable  pencil  dust  off  any  particles  from  the 
black  surface  of  the  plate,  and  then  flow  it  with  collodion  in 
the  same  way  in  which  the  ambrotype  glass  was  covered. 
Wait  for  the  congelation,  or  partial  desiccation  of  the  film, 
and  then  immerse  it  in  the  silver  until  it  assumes  a  creamy 
opacity,  (not  blue,)  and  until  the  solution  flows  off  without 
apparent  oily  streaks.  Then  raise  it  from  the  bath  ;  allow 
the  superfluous  fluid  to  drain  off  into  the  bath,  and  with  bib- 
ulous paper  remove  the  last  drop  from  the  pendent  corner  of 
the  plate.  The  plate  is  next  inserted  in  its  holder,  and  a 
piece  of  the  same  size  placed  over  it.  Previous  to  this  part 
of  the  operation,  the  photographer  must  never  forget  to  clean 
out  the  lower  corner  of  the  plate-holder,  by  means  of  blotting 
paper  or  old  rag.  Nitrate  of  silver  is  apt  to  settle  in  these 
corners  ;  and  these  being  formed  of  separate  pieces  of  glass,  ce- 
mented together,  and  not  of  one  solid  mass,  (which  is  Lewis 
and  Holt's  patent,)  the  nitrate  of  silver  becomes  frequently  de- 
composed by  the  material  of  the  cement,  and  running  up  the 
plate  on  the  collodion  side  by  capillary  attraction,  it  pro- 


MELAINOTYPE  FERROTYPE . 


143 


duces  dark-colored  stains  and  streaks.  Make  it  your  duty, 
therefore,  a  part  of  the  collodion  operation  in  fine,  to  clean 
these  corners  carefully  before  you  take  out  the  plate  from 
the  silver  bath. 

The  time  of  exposure  of  a  melainotype  is  the  same  exactly 
as  for  an  ambrotype.  All  the  instructions,  too,  for  develop- 
ing, fixing,  coloring,  and  varnishing  the  positive  on  glass 
are  valid  here.  I  regard  it  as  preferable  to  color  after  the 
plates  are  varnished,  both  in  this  as  well  as  in  the  preceding 
type.  Owing  to  the  better  conducting  qualities  of  heat  in 
iron  plates  over  those  of  glass,  more  caution  is  required  lest 
the  Japanned  film  becomes  raised  into  blisters.  This  misfor- 
tune is  very  common  with  beginners  on  certain  plates,  with 
the  Excelsior,  perhaps,  less  frequently  than  with  some  others. 

This  type  is  mounted  with  glass,  mat,  and  preserver,  and 
fixed  in  a  case  like  an  ambrotype  ;  or  it  may  simply  be  covered 
with  a  mat,  and  thus  prepared  for  mailing  in  a  letter.  For 
this  purpose  each  corner  is  cut  off  with  a  pair  of  shears,  at 
a  distance  of  one  quarter  of  an  inch  from  the  apex,  and  the  cor- 
responding corners  of  the  mat  are  folded  or  reduplicated  over 
and  under  it,  so  as  to  form  a  compact  piece  out  of  the  two. 
The  melainotype,  as  thus  taken  directly  from  the  model,  is  an 
inverted  picture,  like  the  ambrotype,  but,  unlike  the  ambro- 
toype,  it  can  never  by  a  single  operation  be  otherwise.  In 
the  alabastrine  process  just  described,  the  ambrotype,  it  will 
be  observed,  is  not  an  inverted  picture ;  the  plate  is  inverted, 
and  the  image  is  beheld  through  the  collodion  in  its  natural 
and  direct  position. 


CHAPTER  XXIL 


COLLODION"  NEGATIVES. 

A  collodion  negative  is  an  actinic  impression,  in  which  the 
different  .parts  of  the  image  are,  as  in  the  positives  just  de- 
scribed, laterally  inverted,  and,  when  viewed  by  transmitted 
light,  the  shades  are  where  the  lights  ought  to  be,  and  vice 
versa.  It  is  the  matrix  from  which  positives  are  obtained 
by  direct  contact,  either  on  glass,  or  on  paper,  as  also  by 
means  of  the  lens  in  the  ordinary,  or  in  the  solar  camera. 
Most  of  the  details  of  the  operation  in  the  negative  process 
are  the  same  precisely  as  in  the  positive  process. 

The  glass  is  filed,  cleaned  and  flowed  with  collodion,  as  be- 
fore directed.  It  is  sensitized  too  in  the  same  bath,  and  then  ex- 
posed. Let  the  time  of  exposure  be  from  ten  to  twenty  sec- 
onds in  the  glass-room,  probably  more  ;  much  depends  upon 
the  proper  adjustment  of  the  light,  and  its  concentration  by 
the  lenses.  The  object  in  view  is  to  obtain  much  more  ac- 
tinic action,  not  only  on  the  film,  but  through  the  film,  so  as 
to  produce  a  denser  metallic  reduction  for  the  shades,  which 
in  the  ambrotype  are  lights.  To  guard  against  the  liability 
to  fogging,  a  much  weaker  and  more  acid  developer  is  used 
than  in  the  positive  process.  The  developing  is  carried  on 
as  long  as  the  shades  increase  in  density  by  transmitted  light. 
It  is  quite  an  advantage  in  this  process  to  have  a  small  square 
of  orange-colored  glass  situated  lower  down  than  the  posi- 
tion of  the  negative,  as  you  hold  it  for  the  operation  of  de- 
velopment, in  order  that  the  light  may  come  from  below,  and 
thus  through  the  glass.  If  fogging  sets  in,  or  the  density 
seems  to  be  stationary,  or  even  to  retrograde,  the  negative 
is  developed  as  far  as  circumstances  in  the  present  instance 
will  permit.  If  the  density  of  the  shades  is  so  great  as  to 
prevent  you  from  distinguishing  objects  through  them,  and 
these  shades  are  regularly  tempered  down  through  the  inter- 
mediate tones  to  the  bright  lights,  and  these  lights  are  still 
clear  and  transparent,  it  is  very  possible  that  the  image  is  suf- 
ficiently negative,  and  that  you  have  succeeded  in  your  under- 
taking. It  is  absolutely  necessary  that  you  should  know  what 


COLLODION  NEGATIVES. 


145 


you  have  to  do,  before  you  can  depend  upon  what  you  do, 
or  rely  on  definite  results.  A  true  negative  is  just  what  I 
have  described.  If  the  lights  are  not  clear  and  transparent, 
with  sufficient  detail,  of  course,  intermingled ;  if  the  shades 
are  transparent,  and  not  comparatively  opaque,  so  much  so 
as  to  allow  the  print  of  a  book  to  be  read  through  them;  or 
if  there  are  no  intermediate  tints,  but  your  negative  is  all 
black  and  white  ;  then  you  have  not  succeeded — your  nega- 
tive is  faulty.  We  will  suppose,  however,  that  the  three 
gradations  of  shades,  middle  tones,  and  lights  exist,  but 
that  the  intensity  of  the  shades  is  not  strong  enough ;  there 
is  a  general  weakness  in  the  negative,  and  your  object  is  to 
push  on  the  development,  which  is  found  to  be  ineffectual 
without  producing  a  haziness  or  fogginess  over  the  whole 
print ;  the  conclusion  to  be  drawn  from  this  circumstance  is 
that  the  time  of  exposure  was  too  short.  Another  sitting 
may  remedy  the  evil.  On  the  contrary,  if  when  the  deve- 
loper is  poured  on,  the  reduction  on  the  shades  is  very  ra- 
pid, and  this  reduction  commences,  rushes  with  rapidity  into 
the  lights  before  you  have  time  almost  to  stop  it,  you  may 
fairly  conclude  that  the  time  was  too  long.  But  a  develop- 
er sometimes  may  produce  very  much  the  same  effect ;  for, 
if  the  proportion  of  the  iron  salt,  in  comparison  with  the 
acid  and  the  water,  be  great,  fogging  and  rapid  reduction 
will  certainly  be  the  result.  As  before  remarked,  a  much 
weaker  developer  is  required  in  the  preparation  of  a  nega- 
tive than  in  that  of  a  positive,  and  a  proportionately  larger 
quantity  of  acid  to  check  its  action,  until  the  proper  density 
of  opacity  is  attained  in  the  shades.  (I  use  the  words  shades 
and  lights  in  the  negative,  to  represent  what  they  really  are, 
and  not  what  they  produce  on  the  paper  print ;  shades  are 
dark  and  opaque  ;  lights  are  thin  and  transparent.) 

We  do  not  aim  to  obtain  brilliant  white  silver  reductions 
on  the  negative  ;  for  the  color,  or  metallic  brilliancy  is  altoge- 
ther a  matter  of  little  consequence ;  on  this  account  we  use 
no  silver  solution  in  our  negative  developer.  Where  the 
time  of  exposure  is  not  necessarily  required  to  be  very  short, 
a  pyrogallic  acid  developer  produces  a  very  pleasing  nega- 
tive. 

Negative  Developers. 

Formula  JSFo.  1.    Iron  Developer. 

Sulphate  of  the  protoxide  of  iron,     4  drachms. 

Rain-water,  8  ounces. 

Acetic  acid,  \\  ounces. 

Alcohol,  6  drachms. 

7 


146 


COLLODION  NEGATIVES. 


Formula  JSTo.  2.    Pyrogallic  Acid  Developer, 

Pyrogallic  acid,  3  grains. 

Water,   2  ounces. 

Acetic  acid,  2  drachms. 

Alcohol,  6  drops. 

The  negatives  which  produce  the  softest  prints  are  those 
which  are  produced  by  the  first  development,  where  the 
time  of  exposure  and  the  action  of  the  reducing  agents  have 
been  in  such  relatively  due  proportion  as  to  produce  the 
three  gradations  with  a  proper  amount  of  opacity  in  the 
shades.  This  proportion  can  not  always  be  determined  be- 
forehand, because  of  the  variability  of  the  light,  and  its  ac- 
tinic powers,  of  which  we  know  as  yet  absolutely  so  little. 
We  can  not  determine  the  reason  of  the  widely  diverse  ac- 
tion of  light  at  six  in  the  morning,  and  six  in  the  evening,  or 
at  the  vernal  equinox,  and  the  autumnal.  In  consequence  ol 
this  want  of  definite  knowledge  of  the  prime  cause  that  in- 
stitutes the  actino-physical  changes  in  the  iodo-sensitized  col- 
lodion film,  it  will  frequently  happen  that  the  developed 
image  is  not  perfect ;  the  shades  are  not  endowed  with  suf- 
ficient opacity.  Fortunately  in  such  cases  we  possess  means 
whereby  these  shades,  middle  tones,  and  detail  in  the  lights 
can  all  be  in  relative  proportion  rendered  more  opaque,  and 
as  much  more  opaque  as  may  be  desired.  The  process  by 
which  this  end  is  attained,  is  denominated  the  Intensifying 
or  Redeveloping  process. 

The  image  having  been  developed  as  far  as  possible  in  ac- 
cordance with  the  rules  laid  down,  the  plate  is  thoroughly 
and  carefully  washed  on  both  sides,  and  freed  entirely  from 
every  trace  of  nitrate  or  developer.  Cyanide  of  potassium 
in  solution,  the  formula  of  which  is  given  at  the  end  of  the 
positive  process,  may  be  employed  to  remove  the  undecom- 
posed  iodides  or  bromides,  care  being  taken  not  to  continue 
the  action  of  the  solvent  too  long,  nor  to  apply  it  in  too  con- 
centrated a  condition,  lest  the  fine  markings  of  detail  are  dis- 
solved off  at  the  same  time.  Because,  as  already  mentioned, 
cyanide  of  potassium  is  a  reducing  agent,  as  well  as  a  fixing 
substance,  and  giving  a  silver  salt  so  acted  upon  a  reguline 
appearance,  it  is  regarded  as  the  fixing  agent  proper  for 
collodion  positives ;  whereas,  owing  to  the  properties  pos- 
sessed by  hyposulphite  of  soda  as  a  fixer  alone,  and  not  a 
reducer,  and  because  its  solvent  action  is  not  so  violent  as 
that  of  the  cyanide,  it  is  properly  recommended  to  fix  nega- 
tive pictures. 


COLLODION  NEGATIVES. 


147 


Fixing  Solutions  for  Negatives. 
Formula  No.  1. 
Hyposulphite  of  soda,     ....     5  ounces. 
Water,   10  ounces. 

Formula  No.  2. 
Cyanide  of  potassium,      ....    1  drachm. 
Water,  5  ounces. 

In  case  the  image  is  fixed  with,  the  first  formula,  that  is, 
.with  hyposulphite  of  soda,  the  plate  requires  to  be  washed 
with  the  utmost  care,  for  if  any  of  the  hyposulphite  of  silver 
is  left  in  the  film,  it  will  become  manifest  after  the  drying 
of  the  film,  sometimes  at  the  expiration  of  months,  by  the 
formation  of  a  crop  of  crystals  on  the  surface  that  complete- 
ly ruins  the  picture.  As  soon  as  washed,  the  plate  is  ready 
for  operations  quite  distinct  from  those  in  the  positive  pro- 
cess. 

Intensifying  or  Redeveloping  Process. 

Formula  No.  1.    Depositing  Fluid. 

Iodine,  1  grain. 

Iodide  of  potassium,  1  grain. 

Rain-water,  1  ounce. 

Formula  No.  2.    For  tlie  Stock  Bottle  of  the  same  material. 

Iodide  of  potassium,  1  drachm. 

Water,  2  ounces. 

Iodine  to  saturation. 

Depositing  Operation. 
Take  from  ten  to  twenty  drops  of  this  solution  to  each 
ounce  of  water,  and  flow  the  developed  plate  with  it.  This 
operation  can  be  performed  in  the  diffused  light  of  day.  The 
plate  must  be  kept  in  motion  all  the  while,  and  the  fluid 
poured  off  and  on,  in  order  to  obviate  all  irregular  deposi- 
tion. The  solution  will  gradually  lose  color,  whilst  the  film 
in  the  mean  time  assumes  a  gray  or  yellowish-gray  hue.  If 
the  negative  does  not  require  much  additional  opacity  in  the 
shadows,  it  is  not  necessary  to  carry  on  the  depositing  oper- 
tion  further  than  the  gray  film.  The  plate  is  now  washed 
again. 

Intensifying  Operation. 

Formula  No.  1.    Nitrate  of  Silver. 

Nitrate  of  silver,  30  grains. 

Rain,  or  distilled  water,     ....    1  ounce. 

Take  three  drops  of  this  solution  with  two  drachms  of 
water,  and  cover  the  plate  with  the  fluid.  Pour  the  fluid  off 
and  on  several  times. 


148 


COLLODION  NEGATIVES. 


Formula  No.  2.    Pyrogallio  Acid.  (Stool).) 

2S£rt  •'.      ^SS    [    ^ePinada,k  place. 

Formula  No.  3. 

Of  this  take,  1  drachm.  ) 

Water,  *7  drachms.  >    For  immediate  use. 

Alcohol,     .    .    .    .10  drops.  ) 

To  two  drachms  of  No.  3,  add  ten  drops  of  No.  1 ;  mix  inti- 
mately by  shaking,  and  then  pour  it  upon  the  plate,  and  keep 
it  in  agitation.  The  shades  will  soon  increase  in  blackness 
and  opacity.  The  operation  is  carried  on  to  the  greatest  ad- 
vantage by  holding  the  negative  over  a  light  reflected  from 
below,  as  in  the  dark-room,  or  near  a  doorway  receiving  its 
light  from  the  sky.  Stand  sufficiently  far  back,  and  side- 
wise  of  the  door,  so  that  the  light  does  not  shine  upon  the 
negative  directly  from  the  sky,  but  is  received  as  it  is  re- 
flected upward  from  the  floor,  etc.,  below.  The  shadows 
will  grow  darker  and  darker;  and  the  process  has  to  be  stop- 
ped as  soon  as  the  opacity  is  sufficiently  dense.  Experience 
alone  can  tell  you  exactly  when  to  stop.  The  denser  the 
background  in  the  negative,  if  a  white  screen  were  used,  the 
whiter  the  print  will  be ;  but  the  opacity  may  be  so  great  as 
to  require  an  hour  or  two  for  the  subsequent  printing  opera- 
tion, which  is  very  inconveniently  long.  A  certain  connec- 
tion exists,  therefore,  between  the  negative  effect  and  the 
positive  printing  effect  afterward,  which  experience  has  to 
teach ;  and  even  if  you  do  not  execute  your  own  printing, 
this  connection  must  not  be  lost  sight  of.  In  parts  that  must 
really  appear  white  in  the  paper,  the  opacity  must  be  dense 
enough  to  prevent  you  from  reading  print  through  them ; 
taking  this  for  your  guide,  separate  such  a  part  in  the  pic- 
ture ;  keep  your  eye  steadfastly  upon  it  as  it  increases  in 
darkness,  and  when  it  has  arrived  at  the  point  indicated, 
pour  off  the  intensifying  solution,  and  wash  very  thoroughly. 
It  sometimes  happens  that  the  film  becomes  contracted  by 
this  operation,  or  that  the  fluid  gets  between  the  glass  and 
the  film,  and  thus  the  latter  becomes  loosened,  and  is  liable 
to  peel  off.  Careful  experience  will  teach  you  how  to  retain 
the  collodion  in  its  place. 

Where  many  prints  have  to  be  taken  from  a  negative,  it 
is  quite  requisite  to  varnish  the  film  when  dry.  But  almost 
all  varnishes  have  a  penetrating  effect,  like  oil  of  turpentine 
on  paper,  and  thus  diminish  the  opacity  of  the  negative. 
This  has  to  be  taken  into  consideration,  and  the  negative 


COLLODION"  NEGATIVES. 


149 


must  bo  intensified  in  accordance  deeper  than  required  when 
without  varnish.  The  property  of  a  varnish,  suitable  for 
such  purposes,  must  be  a  sufficient  hardness  of  film  to  pre- 
vent scratches,  insolubility  by  the  heat  of  the  sun,  freedom 
from  any  liability  to  cracking  by  contractility,  perfect  trans- 
parency, as  little  penetrating  power  as  possible,  and  freedom 
from  all  action  upon  the  film. 

Varnish.  Formula. 

White  lac,  4  ounces. 

Picked  sandarac,  4  drachms. 

Alcohol,  (concentrated,)  ....  60  ounces. 

Oil  of  bergamot,  20  drops. 

Dissolve  by  the  aid  of  a  water-bath,  and  filter. 

To  obviate  the  diminution  of  opacity  by  means  of  the  var- 
nish, I  frequently  flow  the  plate  with  a  dilute  solution  of 
gum-arabic  or  gelatine,  which  is  allowed  to  dry ;  and  then 
the  plate  is  varnished. 


CHAPTER  XXIII. 


TRANSFER  PROCESS  OF  COLLODION  POSITIVES  ON"  JAPANNED 
LEATHER,  LINEN,  PAPER,  ETC. 

Before  the  preparation  of  the  iron  plates,  known  as  Me- 
lainotype  etc.,  the  transfer  process  had  more  importance.  A 
transferred  positive  has  all  the  beauty  of  a  melainotype,  with 
the  advantage  of  being  non-inverted,  and  upon  a  medium 
that  suffers  less  from  being  bent.  It  is  especially  suitable 
for  inclosure  in  letters  to  distant  friends.  Any  fine  sub- 
stance, as  very  thin  leather,  linen,  paper,  etc.,  neatly  and 
evenly  varnished  with  black  Japan,  is  adapted  for  the  recep- 
tion of  the  collodion  transfer.  Such  substances  can  be  ob- 
tained from  the  wholesale  dealers  in  photographic  goods ; 
they  can  also  be  prepared  in  the  following  maimer :  Take, 
for  instance,  a  piece  of  fine  leather,  or  oiled  silk,  and  fix  it 
on  a  stretcher,  or  flat  board ;  then  varnish  it  on  one  side  with 
the  following  mixture. 

Black  Japan. 

Chloroform,  8  ounces. 

Asphaltum,  8  ounces. 

Canada  balsam,  2  ounces. 

The  ingredients  when  intimately  mixed  are  poured  in  suffi- 
cient quantity  upon  the  side  to  be  japanned,  and  allowed  to 
dry  at  a  gentle  heat.  The  varnish  will  soon  set,  and  in  a  short 
time  will  be  ready  for  the  transfer  operation.  If  metallic 
plates  have  to  be  japanned,  such  as  the  melainotype,  that 
have  to  be  introduced  into  the  silver  bath,  they  must  pre- 
viously be  coated  with  common  positive  or  negative  var- 
nish, in  order  to  be  prevented  from  exercising  any  injurious 
effect  upon  the  silver  bath,  and  afterward  they  are  japanned 
on  one  side,  as  just  described.  These  plates  are  not  used  in 
the  transfer  process,  but  to  receive  the  image  instead  of  glass. 

The  collodion  on  glass,  when  dry,  or  after  it  has  been 
dried,  adheres  to  the  plate  with  considerable  tenacity.  The 
film  for  transferring,  too,  must  be  of  the  glutinous  kind,  con- 
taining more  ether  than  alcohol.    After  the  image  has  been 


TKAsrsraai  pbocebss  of  collodiox  positives.  151 


fixed,  and  washed,  and  whilst  the  film  is  still  moist,  it  is 
flowed  with  the  following  solution : 

Alcohol,  5  drachms. 

Water,  5  drachms. 

Nitric  acid,  ....  from  12  to  16  drops. 

The  solution  is  immediately  poured  off,  and  the  plate  drained 
of  its  superfluous  fluid.  The  prepared  leather,  etc.,  is  now 
cautiously  laid  upon  the  film,  beginning  in  the  middle,  and 
allowing  either  end  to  fall  gradually  upon  the  collodion,  so 
as  to  exclude  all  bubbles  of  air.  The  leather  is  next  pressed 
with  a  burnishing  tool  all  over  the  posterior  surface,  so  as 
to  bring  it  in  intimate  contact  with  the  film  beneath.  If  the 
operation  be  performed  with  dexterity  and  care,  bubbles  of 
air  may  be  avoided ;  if  any  are  observed,  they  must  be  re- 
moved by  drawing  up  the  leather  gently  before  adherence 
takes  place,  and  then  by  letting  it  down  again  with  more 
caution.  Having  succeeded  in  bringing  the  collodion  film 
and  the  leather  in  juxtaposition,  without  a  single  bubble,  the 
plate  is  warmed  gently  over  an  alcohol-lamp,  after  which  the 
.leather  can  be  removed,  together  with  the  collodion  film  ad- 
hering to  it.  The  leather  is  now  rinsed  in  pure  water,  and 
allowed  to  dry. 

If  it  be  desired  that  the  collodion  picture  shall  be  in  the 
form  of  an  oval,  circle,  or  square,  etc.,  we  proceed  as  follows  : 
Place  a  mat  with  the  proper  opening  upon  the  collodion  pic- 
ture, and  with  a  pointed  style  go  round  the  picture,  cutting  it  as 
it  were  from  the  glass.  All  the  collodion  on  the  outside  of 
this  line  is  next  removed  with  a  piece  of  wood,  as  for  instance, 
the  end  of  a  match  cut  to  a  flattened  point,  and  made  moist. 
By  using  this  like  a  scraper,  and  keeping  it  moist,  the  collo- 
dion will  gradually  disappear,  and  the  surface  will  be  kept 
clean.  The  picture  is  afterward  transferred  to  leather,  en- 
amelled cloth,  etc.,  by  the  method  just  described. 

Transfer  Paper. 
Paper  is  prepared  as  follows  for  receiving  the  collodion 
positive.  Dissolve 

Asphaltum,  3  ounces  in 

Turpentine,  6  ounces. 

Boiled  oil,  8  ounces. 

Afterward  take — 

India-rubber,  (belting,)    ....    1  ounce. 
Camphene,  2  ounces. 

Dissolve  the  latter  by  a  gentle  heat,  and  then  add  it  to  the 
first  solution.    Shake  the  solutions  well  together,  and  then 


152         TRANSFER  PROCESS  OF  COLLODION  POSITIVES. 

allow  the  mixture  to  settle  for  a  few  days.  It  is  afterward 
decanted  into  a  dish.  Ordinary  unruled  fine  paper,  in  pieces 
of  the  proper  size,  is  floated  on  this  bath,  and  afterward 
hung  up  to  dry.  By  repeating  the  process,  the  paper  finally 
receives  a  very  smooth  surface.  It  will  keep  for  any  length 
of  time.  With  a  mixture  of  one  ounce  of  alcohol,  and  three 
drops  of  nitric  acid,  moisten  both  the  collodion  film  and  the 
prepared  paper  surface,  and  pour  the  surplus  back  again  into 
the  bottle.  Dip  the  plate  and  the  paper  into  soft  water  sev- 
eral times ;  then,  laying  the  plate  on  the  table,  place  the  pa- 
per  upon  the  collodion  positive  in  the  manner  already  pre- 
scribed, in  order  to  exclude  bubbles ;  press  them  close  to- 
gether until  the  paper  is  quite  smooth.  The  latter  may  now 
be  raised,  and  removed  from  the  glass,  and  dried. 


CHAPTER  XXIV. 


COLLODION"  POSITIVES  Olt  GLASS  BY  TRANSMITTED  LIGHT. 

Transparent  Positives. 
This  kind  of  picture  is  used  more  especially  for  stereosco- 
pic slides.  Its  application  to  church-windows,  etc.,  for  which 
it  is  so  well  adapted,  has  not  yet  been  introduced  to  any  great 
extent.  A  transparent  positive  may  be  produced  either  by 
means  of  the  camera,  or  by  direct  contact  of  the  negative. 
By  means  of  the  camera  the  proceeding  is  as  follows  : 

In  the  first  place  we  require  a  good  orthoscopic  lens,  or, 
in  fact,  any  lens  that  will  produce  with  an  inserted  diaphragm 
a  clear,  well-defined  picture  of  a  page  of  print,  without  dis- 
tortion of  the  marginal  lines.  Ascertain  the  length  of  the  equal 
conjugate  focus  of  the  lens,  that  is,  half  the  distance  between 
the  object  and  its  image,  when  these  are  of  the  same  size. 
Then  construct  a  square  cylinder  of  thin  wood,  in  which  the 
camera  can  slide  ;  let  the  inside  be  blackened  with  a  solution 
of  ink,  laid  on  twice.  At  the  end  in  front  of  the  lens,  cut 
.  out  an  aperture  of  the  size  of  the  negative,  leaving  a  ledge 
of  three  sixteenths  of  an  inch  all  round  on  which  the  nega- 
tive can  rest.  Fix  the  negative  by  means  of  a  tack  or  small 
pin  in  each  corner.  It  is  inverted  laterally,  that  is,  the 
sides  have  changed  places,  left  being  right,  and  right  left ; 
and  the  collodion  side  is  inwards,  or  facing  the  lens.  This 
compound  camera  is  now  pointed  either  to  a  white  cloud,  or 
directly  to  the  sun.  Focus  the  image  on  the  ground  glass 
with  great  accuracy  ;  it  is  much  more  difficult  to  obtain  the 
right  focus  in  such  work  than  in  ordinary  portraiture,  and  a 
microscope  is  invariably  required  to  obtain  a  sharp  and  cor- 
rect copy.  It  facilitates  the  operation  of  focussing  to  find 
some  small  point,  or  mark,  or  wrinkle,  and  then  to  slide  the 
camera  in  the  cylinder  backward  and  forward,  until  you 
think  you  have  got  the  sharpest  definition,  and  afterward  to 
make  the  final  adjustment  with  the  microscope.  Inasmuch 
as  the  lens  is  within  the  cylinder,  all  the  focussing  has  to  be 
performed  by  means  of  the  sliding  of  the  camera ;  and  when 
7* 


154       COLLODION  POSITIVES  BY  TRANSMITTED  LIGHT. 


once  the  right  focus  has  been  found,  the  cylinder  and  the  cam- 
era are  firmly  fastened ;  and  a  mark  is  made  by  which  at 
any  time  afterward  the  adjustment  can  be  quickly  made, 
without  resorting  to  an  independent  system  of  focussing  on 
each  occasion  when  a  transparent  positive  has  to  be  taken. 

With  the  bright  rays  of  the  sun,  and  an  orthoscopic  lens, 
probably  as  much  as  from  one  to  three  minutes'  exposure  will 
be  required  ;  whereas,  with  an  ordinary  well-corrected  por- 
trait lens,  the  time  will  vary  from  a  quarter  of  a  minute  up- 
ward. It  is  supposed,  of  course,  that  a  small  stop  is  used, 
so  as  to  obtain  a  sharp  and  undistorted  picture.  With  a 
large  diaphragm,  naturally  a  much  shorter  exposure  would 
be  quite  sufficient.  All  the  rest  of  the  operation  of  collo- 
dionizing,  developing,  and  fixing  is  the  same  as  that  already 
described.  The  picture  is  -developed  near  the  pane  of  glass 
which  admits  light  from  below.  A  bright,  transparent  pic- 
ture is  particularly  required  in  this  operation  ;  there  must 
be  no  fogging,  and  the  shades  must  be  pretty  deep  and  dis- 
tinct. 

Such  is  a  general  outline  of  producing  transparent  posi- 
tives on  glass,  by  means  of  the  lens  and  camera  ;  but  there 
are  specialties  that  demand  our  attention.  One  of  these  re- 
fers in  particular  to  the  nature  of  the  negative.  A  bright, 
transparent,  and  clear  negative,  somewhat  less  opaque  in  the 
shadows  than  for  the  common  printing  process  on  paper,  is  best 
adapted  for  the  purpose  in  question.  If  a  negative  had  to 
be  specially  prepared  for  producing  transparent  positives,  I 
would  recommend  its  preparation  as  above  described,  only 
giving  a  trifling  less  exposure,  and  using  a  slightly  stronger 
developer.  The  reduction,  too,  must  be  stopped  the  very 
moment  there  is  the  slightest  tendency  to  veiling.  Finally 
after  the  negative  is  fixed,  supposing  it  to  be  already  suffi- 
ciently intense  not  to  require  any  redevelopment,  (which 
is  a  very  desirable  condition,)  it  is  flowed  with  a  solution  of 
iodine  in  iodide  of  potassium  for  a  few  moments,  taking  care 
to  keep  the  fluid  in  motion  ;  this  operation  must  be  very  short 
in  duration.  Pour  off  the  solution  ;  wash,  and  again  fix  with 
cyanide  of  potassium.  This  operation  may  be  appropriately 
termed  the  Clarifying  Operation,  for  the  negative  becomes 
quite  clear  and  transparent,  from  the  fact  that  in  those  parts 
where  there  was  a  tendency  to  a  veil  or  fog,  the  reduced  sil- 
ver that  produced  it  has  been  converted  into  iodide  of  silver, 
and  dissolved  by  the  cyanide  in  the  second  fixing.  This 
clarifying  operation  must  be  employed  with  extreme  care, 
lest  the  minute  details  might  be  carried  off  at  the  same  time; 


COLLODION  POSITIVES  BY  TRANSMITTED  LIGHT.  155 


Varnishing,  it  is  true,  will  also  reduce  the  amount  of  density 
in  the  shadows,  but  it  does  not  remove  any  of  the  fogging, 
and  besides  this  it  increases  the  opacity  of  the  transparent 
parts ;  in  short,  it  tends  to  diminish  contrast.  On  this  ac- 
count it  is  preferable  not  to  varnish  the  negative. 

By  fixing  the  negative  in  the  holder  with  the  collodion 
side  next  to  the  lens,  the  positive  collodion  picture  will  be 
on  the  right  side  of  the  glass,  erect  and  free  from  lateral  in- 
version. If  it  were  fixed  otherwise,  then  the  positive  would 
be  on  the  under  side  of  the  glass,  and  would  not  appear  so 
brilliant  when  mounted. 

Another  specialty  to  be  observed,  refers  to  the  color  of 
the  positive.  The  shadows,  after  reduction  with  the  proto- 
sulphate  of  iron,  are  grayish  or  silver-white.  For  viewing 
by  reflected  light,  if  they  were  in  their  proper  place,  they 
would  be  endowed  with  a  very  pleasing  aspect ;  but  viewed 
by  transmitted  light,  the  contrast  is  by  no  means  agreeable  ; 
the  shades  are  too  gray.  The  object,  therefore,  is  to  com- 
municate to  them  a  rich  black  hue.  We  effect  this  by  pour- 
ing over  the  film  a  sufficient  quantity  of  a  saturated  solution 
of  bichloride  of  mercury  free  from  acidity.  As  soon  as  the 
film  is  black,  pour  off  the  mercury,  and  wash  the  plate  in 
rain-water. 

The  next  operation  is  to  flow  over  the  plate  a  saturated 
solution  of  cyanide  of  silver  in  cyanide  of  potassium. 

Formula  No.  1. 
Cyanide  of  potassium,     ....    100  grains. 
Kain-water,  2  ounces. 

Nitrate  of  silver  solution,  (50  grains  to  the  ounce,)  as  long 
as  the  precipitate  is  dissolved. 

This  solution,  after  filtration,  is  ready  for  use.  Or  a  solu- 
tion of  cyanide  of  copper  may  be  substituted  for  the  silver 
salt. 

Formula  JSTo.  2. 
Cyanide  of  potassium,    ....    100  grains. 
Kain-water,    2  ounces. 

Nitrate  of  copper  solution  as  long  as  the  precipitate  is  dis- 
solved by  shaking.    Filter  as  before,  and  use. 

The  image  when  flowed  with  either  of  these  menstrua  as- 
sumes an  intense  black  hue.  The  solutions  can  be  used  over 
and  over  again  until  exhausted. 

The  plates  are  now  washed  carefully  and  thoroughly,  and 
again  fixed  with  solution  of  hyposulphite  of  soda,  but  not 
with  cyanide  of  potassium,  because  it  reduces  the  silver  to 


158       COLLODION  POSITIVES  BY  TRANSMITTED  LIGHT. 


a  white  film  again.  This  mode  of  blackening  the  silver  film 
may  be  used  also  as  an  intensifier. 

When  this  operation  is  complete,  the  plate  is  washed  and 
dried,  also  varnished,  unless  the  slide  has  to  be  mounted  with 
a  glass  before  it,  when  the  varnishing  may  be  omitted.  Pre- 
vious to  mounting,  it  may  be  colored  either  on  the  picture 
side  or  on  the  back,  by  which  a  very  rich  effect  is  produced. 
When  positives  are  thus  colored,  they  are  mounted'  with  a 
plate  of  ground  glass  behind  them,  and  thin  transparent  glass 
in  front. 

For  the  magic  lantern,  the  slides  must  be  preserved  as 
transparent  as  possible  ;  consequently  no  ground  glass  is 
used  behind.  The  coloring,  too,  must  be  laid  on,  either  be- 
fore varnishing,  or  afterward,  very  lightly  and  artistically, 
so  as  to  impede  the  passage  of  the  light  as  little  as  possible. 


CHAPTER  XXV. 


ENLARGEMENT  OF   NEGATIVES    BY  THE  ORDINARY  CAMERA. 

Haying  obtained  a  sharp  transparent  positive,  it  is  evident 
that,  by  a  reverse  process,  a  negative  may  be  reproduced, 
and  of  course  as  many  negatives  as  may  be  required.  It  is 
thus  that  photographic  negatives  may  be  stereotyped.  Not 
only  can  we  thus  procure  a  matrix  for  the  reproduction  of  a 
valued  negative,  (a  proviso  which  ought  never  to  be  omit- 
ted,) but  from  such  a  transparent  positive  may  be  obtained 
enlarged  negatives.  The  enlargement  depends  upon  the  ca- 
pacity of  the  lens  of  the  camera.  The  bellows  part  of  the 
latter  admits  of  greater  elongation  and  correlative  lateral  ex- 
pansion than  that  of  the  ordinary  camera.  As  soon  as  we 
have  found  the  distance  of  equal  conjugate  foci,  as  before  di- 
rected, then  by  diminishing  the  distance  between  the  posi- 
tive and  the  lens,  we  increase  the  distance  between  the  lens 
and  the  new  negative.  (The  transparent  positive  is  placed 
in  the  opening  in  front  of  the  lens,  where  originally  the  ne- 
gative was  placed.)  But  in  the  same  proportion  as  this  dis- 
tance is  increased,  in  like  manner  is  the  new  negative  en- 
larged. The  amount  of  enlargement*  will  depend,  as  soon 
as  the  camera  is  arranged,  upon  the  perfection  of  the  lens, 
which,  be  it  ever  so  good,  has  to  be  stopped  down  to  a  small 
aperture,  in  order  to  overcome  spherical  aberration,  which 
causes  distortion,  and  detracts  from  the  sharpness  on  the 
peripheral  parts.  With  the  bright  light  of  the  sun  there  is 
no  difficulty  in  thus  obtaining  a  negative  magnified  ten  times 
diametrically  with  such  a  lens,  and  in  a  very  reasonable 
time.  Thus  a  stereoscopic  portrait  or  view  maybe  enlarged 
into  a  cabinet-sized  picture  or  landscape,  with  but  a  small 
expenditure  of  time  and  expense.  Nor  is  a  large  lens  re- 
quired for  this  operation.  The  same  lens  with  which  the 
original  negative  was  taken  may  be  applied  to  the  purposes 
of  enlargement.  In  making  enlarged  negatives,  however,  we 
require  particularly  a  greater  amount  or  a  greater  intensity 

*  Vide  Chapter  for  the  table  of  distances  and  magnitudes. 


158 


ENLARGEMENT  OF  NEGATIVES. 


of  light,  so  that  with  a  given  light  the  exposure  must  be  so 
much  the  longer.  In  such  cases,  then,  where  the  enlarge- 
ment is  as  great  as  before  mentioned,  it  is  advisable  to  con- 
struct a  system  of  reflectors  in  front  of  the  aperture  for  the 
reception  of  the  negative  or  positive. 

Reflectors  used  as  Co?idensers  of  Light. 
Let  the  aperture  for  the  negative,  etc.,  be  four  inches 
square ;  then  construct  a  frustum  of  a  pyramid  out  of  four 
pieces  of  silvered  glass,  of  the  following  dimensions  :  The  nar- 
row end  of  each  piece  is  four  inches,  the  broad  end  is  14T7o\ 
inches  ;  the  length  of  either  side  is  21T5^  inches.  Fix  these 
pieces  of  glass  in  a  tin  frame,  with  the  silvered  side  inward, 
and  attach  the  frustum  to  the  aperture  for  the  negative. 
When  the  latter  or  a  transparent  positive  is  in  its  place, 
turn  the  camera  (which  for  this  purpose  must  be  fixed  upon 
a  universal  joint)  toward  the  sun ;  it  will  be  found  that  the 
intensity  of  the  light  has  been  greatly  increased.  Such  a 
condensing  reflector  is  calculated  to  condense  all  the  rays 
that  fall  upon  it,  either  by  one  or  two  reflections,  so  that 
they  all  fall  upon  the  negative.  But  the  amount  of  light 
that  impinges  directly  upon  the  larger  base  of  the  frustum 
is  at  least  thirteen  times  greater  than  that  which  falls  upon 
the  smaller  base ;  and  if  there  were  no  loss  of  actinic  power 
by  reflection,  the  light  condensed  on  the  negative  would  be 
thirteen  times  more  than  would  impinge  upon  it  without  the 
aid  of  the  condensers.  If  then  the  light  be  increased  by  ten 
times  in  intensity,  and  the  picture  be  enlarged  by  ten  times, 
the  time  of  exposure  would  remain  the  same. 


CHAPTER  XXVI. 


TRANSPARENT  POSITIVES  BY  CONTACT  BY  THE  WET  PROCESS. 

In  this  operation,  as  in  the  preceding,  a  very  bright,  sharp, 
clear  negative  is  required.  Transparent  positives  by  direct 
contact  are  obtained  best  by  dry  collodion  plates  ;  they  can, 
however,  be  prepared  as  follows :  Let  the  negative  be  var- 
nished and  thoroughly  dry.  Place  it  in  the  plate-holder,  as 
you  would  the.  sensitized  collodion  plate.  Next  cut  out  a 
piece  of  thin  writing-paper  of  the  same  size  as  the  negative, 
and  then  cut  out  of  this  an  interior  piece  of  the  same  shape, 
thus  leaving  a  margin  all  round  of  about  a  quarter  of  an  inch 
in  width.  Place  the  marginal  rectangle  upon  the  negative, 
and  see  that  it  lies  in  contact  all  round.  Now  prepare  a  col- 
lodion plate  ;  sensitize  it,  and  allow  it  to  drain  thoroughly  ; 
then  place  it  also  in  the  plate-holder,  and  in  contact  with  the 
margin  of  paper,  and  close  the  slide  and  shutter.  Previously 
a  cylinder  of  thin  wood,  blackened  with  ink  within,  is  pre- 
pared with  grooves  at  one  end  for  the  reception  of  the  plate- 
holder,  and  open  at  the  other  extremity  for  the  reception  of 
the  light.  Such  a  cylinder  may  be  six  feet  in  length.  The 
object  in  view  is  to  obtain  only  direct  and  parallel  rays  of 
light,  to  counteract  the  effect  arising  from  the  imperfect  con- 
tact between  the  wet  plate  and  the  negative.  Direct  the 
open  end  of  the  cylinder  to  a  white  cloud,  and  then  draw 
the  slide  for  a  moment,  that  is,  a  fraction  of  a  second,  and 
close  it  again.  Probably  this  maybe  too  much  exposure,  in 
which  case  it  will  be  well  to  paste  a  sheet  of  white  paper 
over  the  end  of  the  cylinder,  in  order  to  moderate  the  action 
of  light.  The  plate  is  afterward  taken  out,  developed,  black- 
ened, and  fixed,  as  already  described. 

On  removing  the  plate  from  the  holder,  the  marginal  pa- 
per will  probably  adhere  to  the  wet  collodion  ;  if  so,  remove 
it  carefully,  and  lay  it  on  a  flat  surface  to  dry.  It  is  possi- 
ble .too,  owing  to  the  inequality  of  surface,  that  the  negative 
has  been  wetted  by  the  superincumbent  wet  plate,  in  which 
case  it  must  be  carefully  washed  in  rain-water,  and  dried. 
Without  the  long  cylinder,  oblique  rays  would  enter  from 
all  sides,  and  destroy  ail  the  sharpness  of  the  picture  by  pro- 
ducing thick  lines  out  of  thin  ones.  "Whereas  in  the  man- 
ner prescribed,  vertical  rays  alone  are  admitted  to  the  bot- 
tom, and  entering  perpendicularly  are  not  refracted. 


CHAPTER  XXVII. 


COLLODION  NEGATIVES  OR   POSITIVES   COPIED  FROM  COLLO- 
DION OR  PAPER  POSITIVES. 

In  this  chapter  will  be  described  the  method  of  copying 
photographic  or  typographic  prints.  Three  things  are  abso- 
lutely requisite  in  order  to  secure  a  good  copy ;  these  are,  as 
before,  a  good  lens,  good  light,  sharp  focussing. 

For  the  purpose  of  copying  I  invariably  use  the  full  blaze 
of  the  sun.  Some  artists  pretend  that  the  system  is  false. 
They  take  their  ideas  from  the  effects  produced  on  solid  ob- 
jects, where  the  contrasts  are  so  immensely  exaggerated ; 
and  they  do  not  bear  in  mind  that  on  a  flat  surface  there  can 
be  no  shadows,  because  there  are  no  prominences.  All  the 
contrast  that  can  possibly  be  obtained  in  the  copy,  exists  al- 
ready in  the  original. 

Upon  a  light  built  table  or  board,  two  inches  wider  than 
the  camera,  nail  down  on  either  side  a  ledge  of  wood,  within 
which  the  camera  can  slide  longitudinally.  At  one  foot's 
distance  from  one  end  erect  a  piece  of  board  of  the  same 
width  as  the  long  board,  and  a  foot  high ;  let  it  be  fixed  per- 
pendicular to  the  board  and  to  the  direction  of  the  ledges, 
by  means  of  triangular  braces  near  the  end  of  the  long  board. 
On  the  side  fronting  the  camera,  construct  two  beveled 
ledges,  one  on  either  side,  perpendicular  to  the  base-board, 
of  half-inch  material ;  within  this  a  piece  of  half  inch  board, 
six  inches  wide,  is  correctly  adjusted  by  planing,  so  as  to 
slide  up  and  down  with  facility ;  on  its  surface  on  either  side 
is  a  similar  bevelled  ledge  running  horizontally,  in  which  an- 
other thin  piece  is  made  to  slide  with  ease.  This  last  piece 
is  the  holder  of  the  print  to  be  copied.  By  the  construction  it 
will  be  seen  that  the  holder  admits  of  motion  vertically  and 
horizontally,  and  that  thus  the  print  can  be  accurately  ad- 
justed in  a  correct  position  in  front  of  the  lens,  so  that  the 
center  of  the  print  and  the  axis  of  the  lens  coincide.  The 
print,  too,  will  thus  be  parallel  with  the  ground  glass  in  the  ^ 
camera.    Small  slips  of  tin  plate  are  screwed  on  the  surface 


COPYING   PHOTOGRAPHIC  PRINTS. 


161 


of  the  holder,  in  order  to  clamp  down  the  print,  and  to  pre- 
vent any  unevenness  on  its  surface  by  cockling  from  the 
heat.  Pins  or  tacks  are  inadmissible  here,  because  of  the 
shadows  produced  by  them  on  the  print  to  be  copied.  As 
soon  as  this  mechanical  contrivance  is  complete,  slide  the 
camera  up  to  the  holder,  and  adjust  the  latter  so  as  to  bring 
its  center  in  front  of  the  cap  of  the  lens,  and  with  a  pencil 
draw  a  circle  around  the  cap  and  upon  the  surface  of  the 
holder.  Whilst  the  slides  are  in  this  position,  mark  the  verti- 
cal and  the  horizontal  slide,  so  that  at  any  time  afterward  the 
holder  can  be  brought  into  position  with  great  facility.  The 
holder  is  now  taken  out,  and  the  print  to  be  copied  is  fixed, 
so  that  its  center  coincides  as  near  as  can  be  with  the  cen- 
ter of  the  circle ;  it  is  placed  upside  down,  so  that  its  four 
boundaries  are  vertical  and  horizontal.  Now  slide  the  print- 
holder  into  its  place,  and  slide  back  the  camera  until  the  pic- 
ture on  the  ground  glass  is  of  an  exactly  equal  size  with  the 
original.  A  microscope  is  required  in  this  operation,  in  or- 
der to  focus  with  the  utmost  accuracy.  Do  not  despise  the 
microscope,  it  is  almost  indispensable.  Focus  whilst  the  sun 
is  shining  upon  the  picture.  Use  a  very  small  stop.  Let  the 
sun  shine  from  one  side  slightly,  with  your  back  turned  to- 
ward this  orb.  The  most  agreeable  time  to  copy  by  this 
method  is  early  in  the  morning ;  the  light  is  then  clear,  and 
by  turning  the  table  on  one  side,  the  rays  illumine  the  object 
very  brilliantly,  and  without  any  haze  ;  turn  the  table  always 
so  that  no  shadow  of  the  camera  or  lens  falls  upon  the  ob- 
ject. As  long  as  the  sun  shines,  you  can  thus  copy,  and  copy 
perfectly ;  the  morning  hours  being  personally  more  agree- 
able, photographically  perhaps  not  as  effective  as  toward  noon. 
The  time  of  exposure  will  vary  according  to  the  power  of  the 
lens,  the  size  of  the  diaphragm,  and  the  magnitude  of  the 
copy.  With  a  lens  of  three  inches  focus,  of  C.  C.  Harri- 
son's manufacture,  with  a  diaphragmatic  aperture  of  one  third 
of  an  inch,  and  when  the  copy  is  equal  to  the  original,  an  ex- 
posure of  fifteen  seconds  will  produce  a  rich  negative.  The 
same  conditions  remaining,  the  one  fourth  orthoscopic  lens  of 
Voightlaender,  whose  focus  is  about  twelve  inches,  will  re- 
quire an  exposure  of  between  two  and  three  minutes  to  pro- 
duce the  same  effect. 

By  the  first-named  lens,  an  ambrotype  or  melainotype  will 
require  only  two  or  three  seconds. 

By  adhering  cautiously  to  the  rules  prescribed,  and  above 
all  things  by  very  accurate  focussing,  and  by  taking  care  that 
the  surface  of  the  photograph,  plate,  or  print  is  perfectly 


162 


COPYING   PHOTOGRAPHIC  PRINTS. 


smooth,  and  in  a  plane  parallel  with  the  ground  glass,  copies 
can  be  obtained  that  can  scarcely  be  distinguished  from  the 
originals.  But  a  very  slight  undulation  on  the  surface  of 
the  print,  or  deviation  from  parallelism  is  sensibly  observ- 
able when  the  conjugate  foci  are  equal,  and  much  more  so 
wmen  the  copy  is  amplified.  The  camera,  when  once  ad- 
justed for  the  day,  is  strapped  down  firmly  to  the  board,  so 
that  the  conditions  of  focussing  can  not  be  altered  by  insert- 
ing the  tablet,  etc.  It  is  necessary  to  cover  the  whole  cam- 
era, and  especially  the  posterior  opening,  with  a  dark  cloth, 
lest  a  single  ray  might  penetrate  into  the  interior.  Close 
the  lens  always  with  the  cap  before  you  take  out  or  put  in 
the  slide,  because  it  is  easier  to  move  the  cap  than  the  slide. 
After  the  slide  has  been  taken  out,  wait  until  all  oscillation 
or  vibration  has  ceased,  before  you  remove  the  cap.  Per- 
form all  your  motions  in  this  operation  firmly,  but  with  gen- 
tleness, not  roughly  and  in  haste.  Whilst  the  ground  glass  is 
out,  place  it  where  no  reflection  can  interfere  with  the  print 
to  be  copied.  The  board  on  which  the  camera  slides,  as  also 
all  the  other  parts,  had  better  be  stained  black,  or  of  some 
neutral  tint. 

If  the  light  of  the  sun  could  be  directed  through  a  long 
cylindrical  opening,  and  then  applied  directly  to  the  illumin- 
ation of  the  print,  without  interference  from  reflections  in  all 
directions,  the  operation  would  be  neater  and  more  effectual. 

Where  copying  has  to  be  performed  by  diffused  light,  this 
light  must  be  small  in  quantity,  proceeding  from  a  single 
pane  of  glass,  as  reflected  from  a  white  cloud  or  a  white 
sheet,  and  all  reflections  must  be  carefully  avoided.  The 
management  of  the  light  in  copying  is  reduced  to  very  sim- 
ple conditions — a  single  light  is  all  that  is  required — no  more 
contrast  is  required  ;  see  that  none  is  communicated  by  unne- 
cessary and  extraneous  shadows  from  neighboring  bodies, 
caused  by  secondary  light.  A  single  light,  where  there  are 
no  bodies  in  its  direction  to  the  print,  will  produce  no  shadow, 
consequently  all  shadows  must  proceed  from  secondary  lights ; 
shut  up,  therefore,  every  aperture,  excepting  the  one  which 
is  to  illumine  the  print  or  type  to  be  copied.  These  precau- 
tions will  bring  with  them  success ;  the  neglect  of  them  will 
cause  you  to  quit  copying  with  disgust  for  want  of  success. 
With  such  a  contracted  light,  the  illumination  can  not  by 
any  means  approach  that  produced  by  the  direct  rays  of  the 
sun ;  the  consequence  will  be  firstly  the  necessity  of  using  a 
large  diaphragm,  and  of  thus  diminishing  the  sharpness  of 
the  copy;  and,  secondly,  of  increasing  the  length  of  the  expo- 


COPYING  PHOTOGRAPHIC  PKINTS. 


163 


sure.  The  difference  of  illumination  in  copying  and  in  di- 
rect portraiture  is  very  distinct ;  for  the  latter  purpose  a 
single  light  without  reflection  will  not,  can  not  succeed ; 
whereas  for  copying,  more  lights  than  one  would  be  not  only 
so  much  more  than  sufficient,  but  at  the  same  time  probably 
in  most  cases  injurious.  Do  not,  therefore,  confound  the 
two  operations,  and  blame  the  light  for  your  mismanagement 
of  it,  for  in  nine  cases  out  of  ten  your  want  of  success  is  to 
be  attributed  to  this  mismanagement. 


CHAPTER  XXVIII. 


STEREOGRAPHIC  NEGATIVES  AND  LANDSCAPE  PHOTOGRAPHY. 

Hereafter  I  shall  devote  a  chapter  to  the  stereograph 
and  its  philosophy ;  in  this  I  shall  simply  give  plain  instruc- 
tions for  taking  the  stereoscopic  negatives  by  the  wet  collo- 
dion process.  For  in-door  work,  and  for  out-door  scenery  where 
the  objects  are  close  at  hand,  a  camera  is  required,  which  is  fur- 
nished with  two  lenses  of  short  focus,  and  of  exactly  equal 
power,  for  the  production  of  stereoscopic  negatives.  These 
lenses  are  fixed  in  the  same  horizontal  line ;  and  about  two 
inches  and  a  half  is  the  distance  between  their  centers.  Each 
lens  can  be  attached  to  a  separate  slide,  so  that  this  distance 
can  be  slightly  increased  to  two  inches  and  three  quarters, 
if  found  necessary.  In  the  camera  there  is  a  vertical  septum 
in  the  middle  which  divides  it  into  two  halves,  one  for  each 
lens.  This  septum  is  nearly  in  contact  with  the  collodion, 
and  consequently  makes  a  division  line  between  the  two 
images,  which  are  taken  on  the  same  glass.  The  glasses  for 
stereoscopic  negatives  are  seven  inches  long  by  three  and  a 
half  wide  ;  I  should  prefer  them  eight  inches  by  four,  in  or- 
der to  have  room  for  blunders  and  mishaps  on  the  edges. 
The  operation  of  focussing  is  the  same  here  as  before,  only 
that  there  are  two  lenses  to  be  adjusted.  Fix  upon  a  cer- 
tain object  which  is  to  be  the  central  or  most  important  one, 
and  turn  the  camera  so  that  it  is  seen  in  the  center  of  one  of 
the  pictures  of  the  ground  glass.  Where  architectural  ob- 
jects occur  in  such  pictures,  the  camera  must  be  perfectly 
horizontal,  if  you  intend  the  vertical  lines  to  be  vertical  in 
the  negative.  If  it  happen  that  such  architectural  objects 
can  not  easily  be  comprehended  in  the  negative,  without  tilt- 
ing the  camera,  use  this  expedient ;  for,  after  all,  the  distor- 
tion which  it  produces  on  the  print  can  be  rectified  in  some 
measure  afterward,  by  tilting  the  print  in  the  stereoscope  to 
the  same  amount.  If  portraits  are  to  be  the  principal  things, 
they  must  be  placed  in  such  a  position  artistically  and  photo- 
graphically as  to  appear  well,  and  at  the  same  time  in  perfect 


STEREO  GRAPHIC  NEGATIVES. 


165 


focus;  if  certain  objects  are  to  be  preeminent  in  esteem,  di- 
rect your  attention  upon  them  when  focussing,  and  regard  the 
rest  as  secondary ;  and  finally,  if  the  whole  landscape  is  the 
object,  divide  up  the  focus,  or  focus  in  such  a  manner  that 
the  view  as  a  whole  is  tolerably  sharp ;  this  can  easily  be 
done  by  focussing  an  object  at  some  distance,  and  by  exclud- 
ing all  near  objects  from  the  print.  In  such  cases,  however, 
we  require  long-focussed  lenses.  For  in-door  operations  the 
portrait  combinations  are  used  ;  for  landscapes  a  pair  of  trip- 
lets, or  of  ordinary  view  lenses,  produce  excellent  results. 
The  globe  lens  of  C.  C.  Harrison  is  all  that  can  be  desired 
for  field  work  ;  it  comprehends  a  larger  angle  than  almost  any 
other  lens,  and  produces  an  irreproachable  picture.  Ross,  Dall- 
meyer,  and  Grubb  manufacture  stereoscopic  lenses  for  land- 
scape photography,  with  which  instantaneous  pictures  can  be 
produced,  and  which  in  all  other  respects  are  highly  com- 
mended by  the  intelligent  amateurs  of  Great  Britain.  Jamin's 
view-lenses  produce  very  neat  results,  and  are  besides  lower 
in  price  than  those  already  alluded  to. 

In  the  ordinary  stereoscopic  negative,  as  in  every  negative, 
the  pictures  are  laterally  inverted,  and  when  printed,  this  in- 
version is  corrected  only  for  each  picture  individually,  for 
the  right-side  picture  is  still  inverted  and  in  the  place  of  the 
left-side  picture.  In  consequence  of  this,  the  printed  stereo- 
graphs have  to  be  cut  apart,  and  mounted  so  that  the  right- 
hand  photograph  is  placed  on  the  right  side,  and  the  left- 
hand  photograph  on  the  left  side.  When  taking  pictures  of 
still  life,  as  also  others,  where  the  living  objects  are  not  in 
motion,  it  is  very  easy  to  manage  matters  so  as  to  invert  the 
photographs  on  the  negative.  The  method  is  as  follows : 
Take  a  large-sized  camera-stand,  allowing  sufficient  space 
for  the  camera  to  slide  laterally.  Placing  the  camera  in  the 
right-hand  corner,  focus  the  left-hand  lens.  Next  slide  the 
camera  gently,  or  lift  it  up  and  place  it  in  the  left  corner, 
and  focus  the  right-hand  lens.  The  space  between  the  cen- 
ters of  the  two  pictures  thus  focussed  must  be  about  two 
inches  and  three  quarters.  Whilst  the  camera  is  in  this  posi- 
tion on  the  left  side,  insert  the  sensitized  plate,  take  out  the 
slide,  uncover  the  right-side  cap  for  a  second  or  two,  and 
take  this  picture.  Then  close  up  the  lens,  lift  up  the  camera 
gently  and  place  it  on  the  right  side.  In  this  position  un- 
cover the  left-side  lens  for  the  same  length  of  time.  In  this 
way,  and  in  the  space  of  ten  seconds  or  so,  the  two  pictures 
can  be  taken  in  a  proper  condition  for  printing'  so  as  to  pro- 
duce a  non-inverted  stereograph.    For  such  work  it  would 


166 


STEItEOGRAPHIC  NEGATIVES. 


be  no  difficult  task  to  contrive  a  slide  by  which  a  single  lens 
would  be  all-sufficient;  that  is,  when  the  camera  is  on  the 
left  side,  the  lens  must  slide  to  the  right  side,  and  vice  versa 
on  the  right  side. 

As  soon  as  the  negative  is  thus  taken,  it  has  to  be  devel- 
oped before  it  gets  dry.  The  development  and  fixing  can 
be  performed  in  a  dark  tent  specially  arranged  for  such  pur- 
poses. Various  contrivances  have  been  adopted  in  landscape 
photography  for  these  operations.  For  my  own  part  I  con- 
sider a  simple  hand-cart,  with  iron  rods  from  corner  to  cor- 
ner diagonally,  in  the  form  of  semi-ellipses,  and  covered  with 
a  balloon-shaped  tent,  a  very  practical  accommodation.  But 
each  successful  photographer  is  somewhat  of  a  genius,  and 
can  easily  arrange  a  dark  chamber  according  to  his  own  taste 
and  materials  on  hand. 

Negatives  thus  taken  and  fixed  are  placed  carefully  away 
in  slides  where  they  can  not  be  injured  during  transport- 
ation home.  In  the  evening,  or  the  next  day,  or  at  any  con- 
venient time,  the  negatives  are  examined ;  if  clear,  transpar- 
ent in  the  lights,  and  sufficiently  intense  in  the  shades,  they 
are  varnished.  On  the  contrary,  if  the  opacity  of  the  shadows 
is  not  deep  enough,  although  the  appropriate  gradation  ex- 
ists between  the  lights  and  shades,  it  will  then  be  deemed 
necessary  to  proceed  to  intensification.  Previously  the  edges 
of  the  negatives  must  be  varnished  to  the  depth  of  one  tenth 
of  an  inch  upon  the  collodion,  to  prevent  its  peeling  off  dur- 
ing the  operation.  This  is  effected  by  dipping  the  quill  end 
of  a  feather  into  the  varnish,  and  then  running  along  the 
edge  of  the  collodion  and  of  the  glass,  with  this  portion  of 
the  feather  slightly  inclined,  so  that  the  varnish  does  not  drop 
off,  a  sufficient  quantity  is  attracted  upon  the  collodion  as  you 
proceed.  After  this  put  the  negatives  aside,  that  the  varnish 
may  become  thoroughly  dry  and  hard.  As  soon  as  it  is  dry, 
immerse  the  plates  in  rain-water,  and  allow  them  to  remain 
there  for  about  a  quarter  of  an  hour,  by  which  time  the  col- 
lodion film  will  have  become  saturated  with  this  fluid.  Now 
you  may  commence  the  intensifying  process,  as  before  de- 
scribed in  the  chapter  on  collodion  negatives. 

Instantaneous  Stereographs. 
There  is  no  branch  of  photography  that  has  so  intensely 
attracted  the  attention  of  wealthy  and  intelligent  amateurs 
as  that  of  stereography ;  on  this  account  we  owe  to  them 
most  of  the  discoveries  in  the  art ;  and  the  new  incitement 
that  has  arisen  in  this  department,  that  of  J[nstantaneous  Ac- 


STEREOGRAPHIC  NEGATIVES. 


167 


tinsim,  has  communicated  a  new  impulse  from  which  we  de- 
rive fresh  deductions  and  new  results.  The  co-laborers  in  ste- 
reographic  pursuits  in  Europe,  but  more  especially  in  Great 
Britain,  beginning  with  royalty  downward  to  the  rural  gen- 
try, are  very  numerous,  very  intelligent,  and,  best  of  all,  very 
communicative.  They  take  out  no  patents  for  their  discov- 
eries, they  make,  no  commerce  with  secrets,  odious  things 
which  noble  minds  eschew.  It  is  to  such  a  goodly  host  of 
fellow-soldiers  in  the  stereographic  camp  that  we  must  attri- 
bute the  riches  of  our  knowledge.  That  light  can  act  acti- 
nically in  the  twinkling  of  an  eye  is  no  tax  upon  cultivated  con- 
ceptions ;  for  in  this  same  wink,  which  to  us  is  instantaneous, 
Light  has  run  round  the  earth  several  times ;  in  this  twink- 
ling, Light  has  seen  more  than  man  in  his  age  can  ever  see ; 
in  this  twinkling,  millions  of  fresh  portions  of  light  have 
impinged  on  the  model,  and  have  rebounded  to  the  lens  and 
through  it,  and  have  nestled  upon  the  sensitized  film — we 
are  justified  then  in  expecting  that  instantaneity  in  photo- 
graphy is  feasible.  The  sole  questions  present  themselves: 
What  film  is  sensitive  enough  to  receive  it  ?  What  deve-  \ 
loper  refined  enough  to  produce  the  reduction  ?  The  ques- 
tions are  answered  by  facts.  Instantaneous  stereographs  ex- 
ist in  great  number,  and  the  artists  that  produced  them  have 
bequeathed  to  the  public  their  modus  operandi.  I  can  not 
do  better  than  quote  a  few  instantaneous  processes.  Ail 
amateurs  agree  in  certain  particulars,  which  conduce  to  suc- 
cess. The  light  must  be  very  bright ;  the  atmosphere  very 
clear  /  the  glass  very  clean  *  the  collodion  very  ripe  ;  the  de- 
veloper very  sensitive,  and  the  lens  very  well  corrected,  and 
capable  of  producing  a  sharp  picture  with  a  large  diaphragm; 
the  shorter  the  focus  the  better  within  proper  bounds. 

Instantaneous  Process  of  Lieutenant-  Colonel  Stuart  Worthy. 


The  pyroxyline  is  first  steeped  in  the  iodo-bromized  alcohol, 
and  the  ether  then  added. 


Collodion. 


Ether,  

Alcohol,  spec,  grav.,  .802, 
Iodide  of  lithium,  .  .  . 
Bromide  of  lithium,  . 


1  ounce. 

.  2J-  ounces. 

15  grains. 

.  6-j-  grains. 


Silver  Bath. 

Ke-crystallized  nitrate  of  silver, 
Distilled  water,       .    .    .    .  , 


35  grains. 
1  ounce. 


Iodized  by  leaving  a  couple  of  coated  plates  in  the  bath  for 
several  hours ;  acidified  at  the  rate  of  from  two  to  three 


168 


STEREOGRAPHIC  NEGATIVES, 


drops  of  nitric  acid  to  the  ounce  of  bath.  Leave  the  plate 
in  the  bath  longer  than  you  would  if  the  collodion  contained 
only  iodine. 

Developer. 

Sulphate  of  iron,  2  ounces. 

Distilled  water,  12  ounces. 

Dissolve. 

Acetate  of  lead,  24  grains. 

Water,  2|  ounces. 

Dissolve. 

Mix  the  above  solutions,  and  when  the  precipitate  has  all 
settled,  decant  off  very  carefully,  and  then  add : 

Formic  acid,  (pure,)  2J  ounces. 

Acetic  ether,  6  drachms. 

Nitric  ether,  6  drachms. 

From  this  stock-developing  solution  take  as  much  as  is  re- 
quired, and  add  acetic  acid,  according  to  the  temperature,  gen- 
erally in  about  the  same  quantity  as  the  formic  acid.  The 
developer  is  kept  on  the  plate  until  the  necessaiy  detail  is 
brought  out ;  after  which  the  plate  is  well  washed  and  fixed 
with  a  weak  solution  of  cyanide  of  potassium. 

Intensifier. 

Pour  on  a  saturated  solution  of  bichloride  of  mercury ;  as 
soon  as  the  proper  color  is  attained,  the  plate  is  thoroughly 
washed,  and  a  five-grain  solution  of  iodide  of  ammonium  in 
water  is  poured  on  and  off  until  the  desired  depth  has  been 
attained.  (The  reader  will  comprehend  the  rationale  of  this 
proceeding  by  carefully  perusing  my  remarks  on  this  subject 
in  a  preceding  chapter.)  After  this  the  following  solutions 
are  used : 

No.  1.    Pyrogallic  acid,  ....    12  grains. 


Water,  1  ounce. 

No.  2.    Citric  acid,  50  grains. 

Nitrate  of  silver,  .  .  .  .10  grains. 
Water,  1  ounce. 


Pour  a  few  drops  of  No.  2  into  No.  1,  and  pour  on  and  off 
until  the  negative  has  assumed  the  required  density.  After 
which  wash  the  plate  thoroughly  in  several  waters,  dry  and 
varnish. 

Valentine  Blanchard  prefers  a  bromo-iodized  collodion, 
although  under  certain  conditions  he  admits  that  a  simply 
iodized  collodion  is  more  rapid,  but  at  the  same  time  there 
is  less  contrast.    The  silver  bath  is  composed  of  re-crystal- 


STEEEOGRAPHIC  NEGATIVES. 


169 


lized  nitrate  of  silver,  forty  grains  to  the  ounce  of  distilled 
water,  and  saturated  with  iodide  and  bromide  of  silver.  It 
is  always  supposed  to  be  acid,  to  which  is  added  a  small  quan- 
tity of  moist  oxide  of  silver ;  after  the  solution  has  been  suf- 
ficiently agitated,  it  is  filtered,  and  then  acidified  by  a  weak 
solution  of  nitric  acid,  containing  three  or  four  drops  of  acid 
to  one  hundred  of  water.  This  acid  solution  is  added  very 
cautiously,  until  the  picture  is  quite  clear  and  free  from  fog- 
ging. A  bath  so  prepared  is  very  sensitive  whilst  new,  and 
it  is  only  whilst  new  that  any  bath  is  likely  to  produce  in- 
stantaneous results. 

The  developer  consists  of  the  sulphate  of  the  protoxide  of 
iron,  generally  thirty,  and  frequently  fifty  grains  to  the  ounce 
of  distilled  water,  acidulated  with  glacial  acetic  acid,  because 
the  ordinary  acid  contains  impurities. 

The  negatives,  when  they  require  it,  are  intensified  with  a 
saturated  solution  of  bichloride  of  mercury  in  cold  water, 
until  the  film  is  of  a  uniform  gray  color  ;  they  are  then  washed 
and  treated  with  a  solution  of  iodide  of  potassium,  (one  grain 
to  the  ounce  of  water,)  by  pouring  it  on  and  off,  until  the 
film  assumes  a  greenish-slate  color.  There  should  be  no 
greenish  hue  on  the  wrong  side  of  the  plate,  for  this  is  an  in- 
dication that  the  strengthening  has  been  carried  too  far. 

Hockins  uses  simply  iodized  collodion ;  his  bath  contains 
thirty  grains  of  nitrate  of  silver  to  the  ounce  of  distilled 
water,  and  is  iodized  by  throwing  in  a  proper  quantity  of 
iodized  collodion ;  it  is  then  filtered.  Two  minims  of  pure 
nitric  acid  are  added  to  each  eight  ounces  of  the  bath,  which 
is  prepared  twenty-four  hours  before  using. 

The  developer  consists  of 

Formic  acid,  (strong,)  ....      2  drachms. 

Pyrogallie  acid,   20  grains. 

Distilled  water,  9£  ounces. 

Alcohol,  ounce. 

This  is  kept  on  the  plate  until  the  operation  is  complete. 
Glaudets  Developer. 

Pyrogallic  acid,   ......  20  grains. 

Distilled  water,   *l\  ounces. 

Formic  acid,   1  ounce. 

Alcohol,   6  drachms. 

Instantaneous  Shutters. 
The  means  by  which  light  is  cut  off  instantaneously,  which 
means  very  quickly,  are  various,  and  many  of  them  are  very 
ingenious.    Some  of  these  shutters  are  behind  the  posterior 
8 


170 


STEREOGKAPHIC  NEGATIVES. 


combination  in  the  lens,  and  are  so  graduated  for  other  than 
instantaneous  purposes  as  to  give  a  shorter  exposure  to  the 
sky  than  to  the  foreground.  For  my  own  part  I  prefer  sim- 
plicity, and  I  use  means  in  which  I  have  been  anticipated  by 
Wilson  and  others.  My  cap  is  my  shutter.  Sometimes  I 
use  a  book.  With  both  I  have  succeeded,  and  naturally  sup- 
pose others  can  do  the  same.  I  do  not  despise  the  ingenious 
shutter. 

In  very  many  cases,  with  all  the  preparations  in  a  normal 
condition,  as  we  suppose,  success  does  not  attend  our  ma- 
nipulations. There  is  still,  therefore,  a  yearning  for  some 
method  more  reliable.  I  have  frequently  succeeded  in  taking 
instantaneous  positives,  that  could  not  be  intensified  into  re- 
spectable  negatives.  But  from  a  collodion  positive  we  know 
that  a  collodion  negative  can  very  easily  be  prepared  by 
copying.  In  this  way  many  a  well-valued  view  is  obtained, 
which  otherwise  would  have  to  be  sacrificed.  On  such  oc- 
casions, therefore,  where  there  is  the  least  doubt  of  success, 
it  is  advisable  to  develop  with  the  ambrotype  developer,  con- 
taining nitrate  of  potassa,  nitrate  of  silver,  and  free  nitric 
acid — the  latter,  however,  in  very  minute  quantity.  We  shall 
thus  probably  obtain  a  good  collodion  positive  on  a  melaino- 
type  or  ferrotype  plate.  This  is  afterward  carefully  copied 
into  a  negative.  In  several  instances  I  have  obtained  a  tol- 
erable effect  by  using  solution  of  sulphate  of  iron  without 
any  acid. 


CHAPTER  XXIX. 


NEGATIVES    O  N"  PAPER. 

These  comprehend  the  Talbotype  or  Calotype,  and  the 
Wax-Paper  Process  of  Legray,  and  its  modifications. 

Tlie  Talbotype  or  Calotype  Process. 

This  process  is  a  negative  on  paper.  Talbot  published,  six 
months  before  the  discovery  of  the  Daguerreotype,  his  pro- 
cess with  the  chloride  of  silver ;  and  the  year  following  the 
Calotype,  or,  as  it  is  now  frequently  denominated,  the  Talbo- 
type, was  made  known.  The  object  is  to  obtain  a  deposit  or 
film  of  iodide  of  silver  of  a  fine  and  even  structure  upon  the 
surface  of  paper.  The  best  paper  for  this  purpose  is  of  the 
English  manufacture,  being  sized  with  gelatine,  the  foreign 
papers  being  sized  with  starch. 

There  are  two  methods  of  iodizing  : 

1st.  Float  the  papers  on  a  solution  of  iodide  of  potassium, 
and  allow  them  to  dry  ;  afterward  float  them  on  a  solution 
of  nitrate  of  silver.  By  double  decomposition,  a  film  of  iodide 
of  silver  is  formed  on  the  surface  in  contact  with  nitrate  of 
potassa. 

2d.  Add  a  solution  of  iodide  of  potassium  to  one  of  ni- 
trate of  silver.  Collect  the  yellow  precipitate,  and  dissolve 
it  in  a  strong  solution  of  iodide  of  potassium.  The  paper  is 
floated  for  a  moment  upon  this  solution  and  dried.  It  is 
then  floated  upon  water  which  decomposes  the  salt,  and 
precipitates  the  iodide  of  silver  in  a  very  finely  divided  state 
on  the  surface  of  the  paper.  The  sheets  of  paper  are  then 
dried.  Their  color  is  a  pale  yellow,  and  they  are  as  yet  not 
sensitive  to  light. 

To  Sensitize  Calotype  Paper. 
Float  the  papers,  or  rather  brush  over  their  surfaces  a  so- 
lution of  nitrate  of  silver,  containing  both  acetic  acid  and 
gallic  acid.  Acetic  acid  acts  here  as  elsewhere:  it  diminishes 
the  energy  of  the  decomposition ;  it  preserves  the  whites  of 
the  paper. 


172 


NEGATIVES  ON  PAPER. 


The  Talbotype  process  in  more  definite  terms  stands  as 
follows : 

Float  the  paper  in  the  following  solution  for  a  minute : 

Nitrate  of  silver,     ......    60  grains. 

Distilled  water,      .  2  ounces. 

Hang  up  the  paper  in  a  dark  room  to  dry.    Next  float  it  in 

Iodide  of  potassium,  1  drachm. 

Distilled  water,  2£  ounces. 

for  ten  minutes ;  afterward  it  is  soaked  in  water  for  an  hour, 
in  order  to  remove  the  excess  of  iodide,  and  then  dried.  It 
is  sensitized  by  brushing  over  it  the  following  solution : 

Nitrate  of  silver,  25  grains. 

Distilled  water,  4  drachms. 

Glacial  acetic  acid, ,  1  ounce. 

Saturated  solution  of  gallic  acid,     .    1^  ounces. 

In  a  few  seconds  the  excess  is  allowed  to  flow  oif,  and,  af- 
ter draining,  it  is  placed  between  folds  of  blotting  paper, 
when  it  is  ready  for  immediate  use.  If  the  sensitized  paper 
has  to  be  kept  some  time,  a  much  weaker  solution  of  gallo- 
aceto-nitrate  is  used  than  that  just  prescribed.  To  every 
ounce  of  the  above  solution  add  from  thirty  to  fifty  ounces 
of  distilled  water,  according  to  the  temperature  of  the  cli- 
mate and  the  time  it  has  to  be  kept.. 

An  exposure  of  the  paper  in  the  camera  whilst  still  moist 
for  a  second  or  two  will  produce  a  latent  image,  which  is  de- 
veloped in  full  intensity  by  washing  the  paper  with  a  mix- 
ture of  four  parts  of  the  saturated  solution  of  gallic  acid,  and 
one  part  of  a  solution  of  nitrate  of  silver,  (50  grains  to  the 
ounce  of  water.)  The  image  soon  begins  to  appear,  and  is 
fully  developed  in  a  few  minutes. 

Fixing  of  the  Negative. 

Immerse  the  prints  in  a  solution  of  bromide  of  potassium 
of  ten  grains  to  the  ounce,  or  in  one  of  hyposulphite  of  soda, 
as  was  afterward  indicated  by  Sir  John  Herschel,  of  one 
part  of  the  salt  to  ten  parts  of  water,  until  the  yellow  iodide 
has  been  completely  removed.  The  prints  are  finally  washed 
in  many  waters,  dried  and  saturated  with  white  wax,  which 
renders  them  transparent. 

Several  distinguished  photographers  have  improved  upon 
this  calotype  process,  amongst  whom  we  may  mention  Blan- 
quart-Evrard,  Legray,  Baldus,  Geoffray,  Tillard,  etc.  Amongst 
all  these  improvements  and  extensions  the  wax-paper  process 
of  Legray  is  the  most  extensively  employed.    For  tourists 


NEGATIVES  ON  PAPER. 


173 


it  presents  undeniable  advantages  in  portability  of  material, 
and  less  liability  to  fracture.  The  wax,  too,  is  a  decided  pre- 
servation of  organic  matter  against  the  action  of  nitrate  of 
silver. 

Wax-Paper  Process  of  Legray. 

This  is  the  simplest  of  all  the  processes  for  taking  negatives 
on  paper.  It  differs  from  the  calotype,  inasmuch  as  the  paper 
is  first  waxed  before  sensitization  in  Legray's  process,  where- 
as in  Talbot's  the  waxing  part  of  the  operation  is  the  last. 
The  paper  suitable  for  this  process  must  be  thin,  compact, 
homogeneous,  when  viewed  by  transmitted  light,  and  the 
sizing  of  the  paper  must  have  been  carefully  performed.  The 
English  papers,  although  perhaps  the  finest,  are  not  suitable, 
from  the  fact  that  they  have  been  sized  with  gelatine,  which 
presents  great  difficulty  in  the  waxing.  Saxony  negative 
paper  is  considered  the  best. 

Waxing  of  the  Paper. 
Obtain  pure  white  wax  from  the  bleacher's,  or,  in  case  this 
can  not  be  procured,  make  use  of  the  purest  yellow  wax  that 
can  be  had.  Next  prepare  a  water-bath  in  which  water  can 
be  kept  boiling,  either  by  lamps  or  a  charcoal-fire.  On  the 
lid  of  the  water  bath  place  a  porcelain  or  metallic  plate,  and 
when  hot,  rub  the  surface  with  the  wax  until  it  is  covered 
uniformly  with  a  layer  of  melted  wax.  Place  upon  this  a 
piece  of  paper  to  be  waxed.  Rub  its  surface  in  like  manner, 
until  it  is  uniformly  covered  and  transparent ;  and  proceed  in 
this  manner  until  a  pile  of  eight  or  ten  papers  is  thus  formed. 
If  the  dish  is  sufficiently  large,  place  a  piece  of  paper  by  the 
side  of  the  pile,  and  then  if  the  uppermost  paper  on  the  pile 
is  quite  transparent  with  wax,  place  it  upon  the  dry  paper; 
upon  this  place  another  sheet  of  un waxed  paper,,  and  then  on 
this  the  second  one  from  the  pile,  and  proceed  thus  until  all 
the  waxed  papers  are  interleaved  with  dry  sheets.  The  in- 
tention of  this  operation  is  to  get  rid  of  the  excess  of  wax. 
Repeat  this  operation  until  the  object  is  effected.  Use  a  pad 
of  cotton,  and  gentle  pressure  on  the  top  of  the  pile  as  you 
proceed,  but  be  very  careful  not  to  make  a  single  crease, 
otherwise  the  sheet  in  question  is  utterly  spoiled.  As  soon 
as  the  paper  ceases  to  shine  from  the  melted  wax,  it  is  time 
to  stop  any  further  removal  of  wax.  The  sheets  of  paper, 
that  have  served  as  interleaves,  may  be  used  in  the  prepara- 
tion of  the  next  batch  of  waxed  papers.  The  papers  thus 
prepared  are  separated,  and  when  the  wax  has  congealed  in 


NEGATIVES  ON  PAPER. 


their  fibrous  structure,  they  are  put  away  for  future  use  be- 
tween plates  of  clean  glass. 

Iodizing  of  the  Paper. 

Formula  of  Legray. 

Rice-water,*  25  ounces. 

Sugar  of  milk,  1  ounce. 

Iodide  of  potassium  or  ammonium,     3  drachms. 
Bromide  of  potassium,      ....  48  grains. 

Mix,  dissolve,  and  filter.  It  is  necessary  to  be  supplied 
with  an  abundance  of  this  bath,  in  order  that  the  papers  can 
easily  be  submerged,  in  which  there  is  considerable  difficulty 
by  reason  of  the  fatty  nature  of  wax.  This  bath  can  be  pre- 
served a  long  time  if  kept,  after  using,  in  well-stoppered  bot- 
tles. 

When  about  to  use  this  bath,  pour  it  into  one  of  the  deep 
dishes  employed  in  other  operations  in  photography,  such  as 
for  albumenizing  or  for  toning,  and  let  it  be  two  or  three  inches 
in  depth  when  poured  in. 

Take  each  paper  by  two  opposite  diagonal  corners,  and 
bending  it  into  a  hollow  curve,  immerse  first  one  of  the  two 
other  diagonal  corners,  and  then  the  other  ;  move  the  paper 
backward  and  forward,  so  as  to  get  the  fluid  over  it,  grad- 
ually lowering  the  two  corners  held  in  the  hands.  Finally, 
by  means  of  a  glass  triangle  or  bent  glass  rods,  press  the 
sheet  entirely  beneath  the  surface  of  the  liquid,  and  re- 
move all  bubbles.  Proceed  in  like  manner  with  all  the 
rest,  carefully  avoiding  all  bubbles  between  the  papers.  In 
about  two  hours  the  papers  will  be  sufficiently  impregnat- 
ed with  the  iodizing  solution ;  after  which  they  are  taken 
out  singly  by  first  raising  one  corner  with  a  glass  rod,  and 
then  seizing  this  with  the  left  hand,  it  is  removed  from  the 
liquid  and  allowed  to  drain  for  a  moment,  and  finally  hung 
upon  varnished  hooks  to  dry ;  or  the  papers  may  be  suspend- 
ed on  a  line  by  clamping  each  upper  corner  by  means  of  a 
clothes-pin.  Great  care  is  required  so  as  not  to  produce  any 
wrinkle  or  crease  in  the  papers  in  any  of  these  operations. 
Several  iodizing  solutions  have  been  proposed  ;  the  following 
with  whey  or  serum  is  found  to  work  well. 

*  Take  seven  ounces  of  rice  and  bruise  it ;  then  boil  it  in  seven  pints  of 
rain  or  distilled  water.  As  soon  as  the  rice  yields  beneath  the  fingers,  the 
boiling  has  been  carried  on  far  enough.  The  water  is  decanted,  and  to  this 
are  added  forty-six  grains  of  isinglass  to  each  pint  of  rice-water,  and  the  mix- 
ture is  again  boiled. 


NEGATIVES  ON  PAPER. 


175 


Whey*  or  serum,  .  . 
Sugar  of  milk,f  .  . 
Iodide  of  potassium,  . 
Bromide  of  potassium, 


25  ounces. 

4  drachms. 

3  drachms. 
48  grains. 


To  the  first  of  the  two  preceding  formulas,  containing  rice- 
water,  which  is  that  of  Legray,  the  author  of  the  process 
was  in  the  habit  of  adding  a  small  quantity  of  the  cyanide 
and  fluoride  of  potassium,  which  are  regarded  now  as  of 
little  or  no  consequence. 

When  removed  from  the  iodizing  bath,  the  papers  have 
changed  their  appearance ;  they  are  now  in  a  spongy  condi- 
tion and  devoid  of  transparence  ;  but  by  heat  they  may  be 
restored  to  their  original  state.  They  frequently  assume  a 
violet  color.  When  dry,  the  sheets  of  paper  are  placed  one 
over  the  other,  between  pieces  of  blotting-paper,  and  packed 
in  a  well-closed  card-board  box  for  future  use. 

Sensitization  of  the  Paper. 
The  alkaline  iodide  in  the  waxed  paper  is  converted  into 
iodide  of  silver  by  immersing  the  sheets  in  the  following 
aceto-nitrate  of  silver  bath  : 

Re-crystallized  or  pure  nitrate  of  silver,  ...    7  drachms. 

Glacial  acetic  acid,  7  drachms. 

Distilled  water,  12  ounces. 

Filter  the  bath  into  the  appropriate  dish  and  sensitize  one 
sheet  at  a  time,  or  at  least  do  not  place  one  sheet  over  an- 
other, and  take  care  to  break  up  all  bubbles  on  the  surface 
of  the  wax-paper.  After  remaining  two  or  three  minutes 
in  this  bath,  each  sheet  is  taken  out,  immersed  in  a  dish  of 
rain-water,  well  washed,  and  then  immersed  in  a  second. 
Afterward  it  is  taken  out,  allowed  to  drain,  pressed  between 
folds  of  bibulous  paper  until  it  is  no  longer  wTet,  but  simply 

*  Whey  is  obtained  by  boiling  a  couple  of  quarts  of  skimmed  milk,  and 
then  adding,  as  soon  as  it  begins  to  rise,  acetic  acid  drop  by  drop  until  the  curd- 
ling or  coagulation  is  complete.  The  whole  is  then  poured  into  a  muslin  bag 
and  filtered.  When  it  has  cooled  down  to  about  100°  or  blood  heat,  the  white 
of  an  egg  well  beaten  is  added  and  stirred  up.  The  liquid  is  again  made  to 
boil,  and  by  the  coagulation  of  the  albumen,  the  whey  becomes  clarified.  It 
is  filtered  a  second  time,  and  is  then  ready  for  use. 

\  Sugar  of  milk  is  concentrated  whey,  or  that  part  which  crystallizes  when 
whey  is  evaporated  to  a  syrupy  consistence.  This  sugar  of  milk,  or  lactin, 
as  it  is  also  called,  is  purified  by  animal  charcoal  and  again  crystallized.  It 
forms  white,  translucent,  four-sided  prisms  of  great  hardness.  It  is  solu- 
ble in  five  or  six  times  its  weight  of  cold  water ;  its  taste  is  feebly  sweet,  and 
feels  gritty  between  the  teeth.  It  enters  into  combination  with  the  protox- 
ide of  lead,  and  is  converted  into  grape  sugar  by  boiling  with  dilute  mineral 
acids.    It  can  be  made  to  ferment,  but  docs  not  do  so  spontaneously. 


176 


NEGATIVES  ON  PAPER. 


moist.  In  tliis  condition  it  may  be  placed  between  two- 
pieces  of  clean  glass  and  exposed  immediately,  or  it  may  be 
gummed  along  the  edges,  and  then  pasted  upon  a  sheet  of 
card-board  and  dried  for  future  use. 

De  Champlouis  has  introduced  an  improvement  into  this 
part  of  the  process.  As  soon  as  the  sheets  are  removed 
from  the  aceto-nitrate  bath,  each  is  placed  whilst  still  moist 
on  the  glass  destined  to  receive  it  in  the  plate-holder ;  it  is 
then  carefully  pressed  on  the  surface  by  means  of  a  small 
piece  of  sponge,  in  order  to  expel  any  bubble  of  air  which, 
by  remaining  between  the  paper  and  the  glass,  might  pro- 
duce uneven  reductions.  On  the  sensitized  paper  a  sheet  of 
blotting-paper  is  in  like  manner  applied  by  the  sponge,  and 
afterward  a  sheet  of  wax-paper  or  wax-cloth,  which  sub- 
serves the  purpose  of  a  final  pressure.  These  two  sheets 
must  be  thoroughly  moistened  with  distilled  water ;  they 
form  a  sort  of  cushion,  which  is  pressed  together  by  a  second 
glass  of  the  same  dimensions  as  the  first.  The  whole  arrange- 
ment may  then  be  placed  in  the  plate-holder,  for  it  is  ready 
to  receive  the  view  immediately,  or  at  any  time  within  twelve 
days.  By  this  expedient  the  paper  dries  very  slowly  from 
the  edges  to  within.  No  washing  is  required  before  ex- 
posure, which  is  a  great  saving  of  time. 

Iodized  wax-paper,  whatever  may  be  its  color  before, 
whether  yellow,  reddish,  or  violet,  is  very  quickly  bleached 
in  the  silver  bath. 

Exposure  to  the  Vieio,  etc. 

The  sensitized  sheets,  however  prepared,  must  be  pro- 
tected against  all  access  of  light,  otherwise  they  will  be 
utterly  spoiled.  There  are  changing-boxes  to  be  had  for 
the  reception  of  waxed  paper  sheets  as  also  for  dry  plates  ; 
these  are  so  arranged  as  to  contain  a  certain  number  of 
sheets  or  plates,  and  to  expose  one  at  a  time  without  any 
injury  to  the  rest.  Without  such  an  arrangement,  the  tour- 
ist will  be  obliged  either  to  have  as  many  plate-holders  as 
plates,  or  to  have  a  small  dark-chamber  in  which  the  hands 
can  make  the  requisite  changes  by  feel.  The  time  of  ex- 
posure of  course  is  variable,  according  to  temperature  and 
the  brilliancy  of  the  light.  Two  or  three  minutes  in  a  good 
light  will  in  general  be  sufficient ;  in  ordinary  light  on  an 
average  from  ten  to  fifteen  minutes  will  be  required. 

Development  of  the  Image. 
This  operation  may  be  performed  right  away  or  any  time 
within  twenty-four  hours.    In  extreme  cases  the  develop- 


NEGATIVES  ON  PAPER, 


177 


ment  may  be  postponed  for  a  week ;  but  the  best  results  are 
obtained  by  developing  immediately  after  exposure.  The 
image,  as  a  general  thing,  is  not  visible  when  taken  from  the 
plate-holder,  excepting,  perhaps,  in  parts  especially  where 
the  paper  has  been  well  washed.  The  most  constant  de- 
veloper is  that  of  Crookes. 

Heat  in  a  glass  flask  twenty  fluid  ounces  of  concentrated 
alcohol  to  near  the  boiling  point,  and  then  add  four  ounces 
and  a  half  of  gallic  acid ;  Alter  this  solution  into  another 
vessel  containing  seventy-two  grains  of  glacial  acetic  acid. 
This  forms  the  stock  solution  of  gallic  acid  which  will  keep 
for  an  indefinite  time.  It  has  a  brownish  color,  but  it  is 
clear. 

When  about  to  develop  a  picture,  measure  out  two  fluid 
ounces  of  rain-water,  to  this  add  half  a  drachm  of  the  alco- 
holic solution  of  gallic  acid  and  seven  minims  of  a  solution 
of  nitrate  of  silver  containing  eighty-six  grains  to  the  ounce 
of  water. 

Th6  sheets  of  paper  are  kept  submerged  in  this  bath  for 
about  half  an  hour,  by  means  of  the  glass  rod  or  triangle, 
when  the  development  will  be  complete,  which  must  be  de- 
termined by  experience. 

De  Champlouis  develops  as  follows  : 

In  the  first  place  the  paper  is  previously  passed  through 
the  silver  bath,  in  order  to  restore  its  humidity,  if  it  is  al- 
ready dry  ;  it  is  next  placed  on  a  plate  of  window-glass  and 
floated  with  a  thin  layer  of  gallic  acid  solution  ;  the  image 
appears  with  great  rapidity,  owing  to  the  quantity  of  silver 
in  the  moistened  paper ;  notwithstanding  this,  the  operator 
can  easily  follow  the  development.  By  pursuing  this  plan, 
spots  and  other  mishaps  are  avoided. 

Whichever  plan  is  pursued,  the  temperature  must  always 
be  at  about  80°  ;  the  developing  solutions  can  be  used  only 
once,  and  are  then  accumulated  and  reduced.  Whilst  the 
paper  is  developing,  a  dirty  deposit  appears  gradually  to 
cover  its  surface  ;  it  need  not,  however,  cause  any  anxiety. 
The  surface,  too,  becomes  spongy  and  porous  after  develop- 
ment— a  condition  which  is  removed  afterward. 

If  the  exposure  has  been  too  short,  the  image  is  very  slow 
in  appearing,  unless  an  excess  of  aceto-nitrate  of  silver  be 
used,  and  even  then  there  is  a  want  of  vigor,  and  especially 
of  the  middle  tones.  Such  a  negative  will  produce  only 
blacks  and  whites  in  the  positives  printed  from  it. 

If,  on  the  contrary,  the  time  has  been  too  long,  the  surface 
presents  a  red  tint,  and  the  development  commences  with 
8* 


178 


NEGATIVES  ON  PAPER. 


•  great  rapidity  on  every  part  simultaneously,  and  soon  as- 
sumes a  uniform  shade  which  takes  away  all  contrast.  For 
this  there  is  no  remedy ;  so  that  a  short  exposure  is  prefer- 
able, because  a  certain  degree  of  vigor  in  the  latter  case,  as 
well  as  contrast,  can  in  general  be  obtained.  The  develop- 
ment is  to  be  observed,  as  it  progresses,  by  transmitted  light, 
otherwise  you  might  be  deceived  by  the  gray  deposit  already 
alluded  to,  and  think  the  negative  spoiled. 

If  the  time  has  been  about  right,  the  print  will  appear 
possessed  of  the  right  gradations  of  light  and  shade,  and  of 
proper  density  of  shade.  As  soon  as  the  darkest  parts  are 
so  opaque  as  to  prevent  an  object  from  being  distinguished 
through  them,  the  development  maybe  considered  complete. 
All  further  action  is  then  stopped  by  immersing  the  nega- 
tives in  water  and  washing  it  well  by  agitation,  or  by  plac- 
ing it  on  a  plate  of  glass  and  then  washing  it  from  the  tap,- 
first  on  one  side  and  then  on  the  other. 

Fixing  of  the  Image, 
This  is  effected  by  allowing  the  paper  to  remain  for  a 
quarter  to  half  an  hour  in  a  solution  of 


or  until  all  the  yellow  color  on  the  white  parts  has  disap- 
peared. The  print  is  then  well  washed  as  before,  and  finally 
left  in  a  vessel  of  water  for  a  number  of  hours.  Finally  it  is 
taken  out,  allowed  to  drain,  and  dried  between  folds  of  blot- 
ting-paper. 

When  dry  the  papers  have  lost  their  brilliancy,  they  have 
a  spongy  appearance,  and  as  if  covered  with  an  infinite  num- 
ber of  small  protuberances,  such  as  are  caused  by  the  iodiz- 
ing solution.  The  brilliancy  can  be  restored  and  the  spongy 
appearance  be  removed  by  holding  the  papers  over  a  fire,  or 
by  placing  each  between  sheets  of  blotting-paper  on  a  water- 
bath,  or  finally  by  running  a  hot  iron  over  each,  so  protected 
with  bibulous  paper.  The  iron,  however,  must  not  be  hotter 
than  boiling  water.  The  wax-paper  negatives  are  now  com- 
plete, and  are  ready  for  use  ;  from  them  positives  on  paper 
are  obtained  as  from  glass  negatives.  When  not  in  use, 
they  are  preserved  in  a  portfolio. 

Geojf ray's  Process  with  Cerolein  for  taking  Paper  Negatives, 
The  author  separates  the  cerolein  from  the  myricin  and 

cerin  of  bees-wax  as  follows  : 

Dissolve  five  ounces  of  yellow  or  white  wax  in  ten  ounces 


Hyposulphite  of  soda, 
Kain-waier,  .    .    .  . 


2  ounces. 
16  ounces. 


NEGATIVES  ON  PAPEE. 


179 


of  alcohol  in  a  retort,  by  means  of  heat  raised  to  the  boiling  t 
temperature  ;  receive  the  distillate  in  a  cool  receiver,  until 
the  wax  is  completely  dissolved.  The  melted  wax  is  then 
poured  into  a  vessel  to  cool ;  gradually  the  myricin  and  cerin 
solidify,  and  the  cerolein  remains  alone  in  solution  with  the 
alcohol,  which  is  separated  by  pouring  it  upon  a  fine  muslin 
sieve,  and  finally  being  mixed  with  the  distillate,  it  is  filtered 
through  paper.  This  forms  the  stock  solution  of  cerolein 
No.  1. 

Secondly,  dissolve  in  three  drachms  of  alcohol  (spec,  grav., 
.849)  four  drachms  of  iodide  of  ammonium,  (or  of  potas- 
sium,) twelve  grains  of  bromide,  either  of  ammonium  or  of 
potassium,  and  twelve  grains  either  of  fluoride  of  ammonium 
or  of  potassium. 

To  twelve  grains  of  freshly  prepared  iodide  of  silver  add 
drop  by  drop  of  a  concentrated  solution  of  cyanide  of  po- 
tassium, until  the  former  is  dissolved,  and  then  mix  this  with 
the  alcoholic  solution  of  the  iodides,  etc.  There  will  be  a 
deposit  of  salts  undissolved  in  this  mixture,  which  is  bottle 
No.  2. 

Of  these  two  solutions  the  author  takes,  when  about  to 
use,  about  twenty  drachms  of  No.  1  and  two  drachms  of 
No.  2,  and  filters  into  a  porcelain  dish.  This  forms  the  bath 
in  which  the  papers  are  immersed  for  about  a  quarter  of  an 
hour,  five  or  six  at  a  time,  until  the  solution  is  exhausted. 
The  papers  when  dry  have  a  rosy  tinge.  The  operations  of 
sensitizing,  etc.,  are  the  same  as  in  Legray's  process. 

Turpentine  and  Wax  .Process  of  Tillard. 
White  wax,  in  small  pieces,  is  digested  in  the  essence  of 
turpentine  for  several  days  ;  the  solution  is  then  decanted 
and  filtered.  To  every  three  ounces  of  this  solution  add 
seven  grains  of  iodine,  which  is  immediately  dissolved  with- 
out discoloration,  or  if  any  be  produced,  expose  the  mixture 
to  the  sun.  Now  add  about  from  forty  to  forty-five  drops  of 
castor  oil,  pure  and  freshly  made,  to  the  above  quantity  of 
wax  and  turpentine.  This  forms  the  bath  when  filtered,  in 
which  the  papers  have  to  be  immersed  for  five  minutes  or 
so.  They  are  then  sensitized,  when  dry,  in  the  following 
bath : 

Nitrate  of  silver,  1  drachm. 

Nitrate  of  zinc,  2£  drachms. 

Acetic  acid,  2£  drachms. 

AVater,  3  ounces. 

The  paper  is  then  washed  carefully  and  dried.    After  ex- 
posure, the  prints  are  developed  by  immersing  them  in 


180 


NEGATIVES  OX  PAPER. 


Distilled  water,  5  ounces. 

Saturated  solution  of  gallic  acid,  .  5  ounces. 
Acetic  acid,  1  ounce. 

To  which  is  added  a  small  quantity  of  a  fresh  solution  of 
nitrate  of  silver.    This  process  is  said  to  be  very  rapid. 

As  before  mentioned,  various  improvements  have  been 
made  in  the  calotype  and  wax-paper  processes,  amongst 
which  I  shall  finally  give  the  wet-paper  negative  process  of 
Humbert  de  Molard,  owing  to  its  simplicity  and  the  rapid- 
ity of  its  action. 

Wet-Paper  Negative  Process  of  Humbert  de  Molard. 
The  papers  are  floated  for  five  minutes  on  the  following 
solution : 

Distilled  or  rain-water,  6  ounces. 

•  Iodide  of  ammonium,  2  drachms. 

They  are  then  taken  out,  hung  up,  and  dried.  This  paper 
will  not  keep  long,  and  must  not,  therefore,  be  prepared 
long  beforehand.  With  most  papers,  that  is,  those  which 
are  sized  with  starch,  a  violet  color  is  produced  by  this  float- 
ing, owing  to  the  free  iodine  generally  existing  in  iodide  of 
ammonium. 

When  dry  and  about  to  be  used,  float  each  sheet  on  the 
following  bath  : 

Distilled  or  rain-water,     ....  6  ounces. 

Nitrate  of  silver,  3-J-  drachms. 

Nitrate  of  zinc,  l-£  " 

Acetic  acid, .   1%  " 

It  is  then  placed  with  its  moist  side  downward  on  a  clean 
piece  of  glass  and  exposed  to  the  object,  taking  care  to  make 
allowance  for  the  thickness  of  the  glass.  From  three  to 
thirty  seconds  will  produce  the  required  result.  The  paper 
is  next  floated  on  the  developer,  which  consists  of 

Water  saturated  with  gallic  acid,  6  ounces. 

Water  saturated  with  acetate  of  ammonia,  .    .     from  48  to  60  drops. 

The  image  appears  with  great  rapidity,  and  its  development 
has  to  be  carefully  watched.  The  washing  and  fixing  are 
performed  as  usual.  When  dry,  the  negative  prints  are 
waxed,  in  order  to  give  them  the  requisite  transparence  for 
the  printing  operation. 

Improved  Calotype  Process  by  Pricliard. 
Take  a  sheet  of  iodized  Turner's  paper,  half  an  inch  wider 
and  longer  than  a  plate  of  glass  fitting  in  the  dark  slide  for 
the  dry  collodion  process  ;  pin  it  on  to  a  board  in  the  usual 


NEGATIVES  ON  PAPEE. 


181 


way,  and,  with  a  glass  rod,  spread  over  the  paper  a  solution 
composed  of 


Allow  this  to  remain  on  the  paper  one  minute,  and  then,  care- 
fully and  evenly,  pour  one  ounce  of  water  over  the  paper, 
which  is  easily  done  by  holding  the  board  on  which  it  is 
pinned  slantingly,  and  take  care  that  the  lower  edge  of  the 
paper  reaches  just  beyond  the  corresponding  edge  of  the 
board.  Repeat  this  washing  a  second  and  a  third  time,  and 
then  pin  up  the  paper  to  dry,  or  it  may  be  dried  between 
folds  of  blotting-paper.  Now  turn  the  sensitized  surface 
downward  on  a  sheet  of  white  blotting-paper,  and  placing 
the  plate  of  glass  upon  the  non-sensitized  side,  with  a  little 
thick  gum  attach  the  overlapped  edges  of  the  paper  to  it.  If 
the  paper  lies  even — and  it  will  do  so  if,  when  slightly  moist, 
it  be  gummed  to  the  glass,  and  afterward  dried — it  may  then 
be  exposed  for  a  few  minutes  to  the  view.  The  time,  of 
course,  has  to  be  learned  by  experience  for  given  intensities 
of  the  light  and  the  power  of  the  lens. 

After  it  has  been  exposed,  separate  the  paper  from  the 
glass  with  a  penknife,  and  develop  the  picture  with  a  solu- 
tion of  gallic  acid,  to  which  has  been  added  two  drops  of  the 
silver  solution  to  each  drachm  of  the  gallic  acid  solution. 
The  picture  comes  out  very  quickly,  and  when  it  is  fairly 
out,  the  development  is  completed  with  the  gallic  acid  solu- 
tion alone. 

Fix  with  a  weak  solution  of  hyposulphite  of  soda ;  wash, 
dry,  and  wax  by  means  of  a  hot  iron,  white  wax,  and  blot- 
ting-paper. 

The  points  requiring  most  care  are  : 

1.  To  wash  evenly,  and  so  as  not  to  allow  any  portion  of  the 
paper  to  escape  washing,  as  such  portion  would  take  no  im- 
pression and  spoil  the  picture. 

2.  Not  to  expose  before  the  paper  is  evenly  dry. 

3.  To  be  very  careful  that  the  back  of  the  paper  is  kept 
clean  and  untouched  from  any  of  the  chemicals. 


Nitrate  of  silver, 
Distilled  water, 
Glacial  acetic  acid, 


28  grains. 
1  ounce. 
10  drops. 


CHAPTER  XXX. 


POSITIVE  PRINTING. 

Printing  on  Plain  Paper,  on  Albumenized  Paper,  on 
Arrow-Hoot  Paper. 

The  theory  and  practice  of  positive  printing  are  second 
only  in  time,  not  in  importance,  to  the  theory  and  practice 
of  the  negative ;  it  is  rare,  however,  that  the  same  amount  of 
care  and  labor  is  bestowed  upon  this  department  as  upon 
that  of  taking  a  negative.  We  run  all  sorts  of  risk,  make 
every  effort,  incur  immense  expenses  in  order  to  secure  a 
first-rate  negative,  and  then  frequently  abandon  the  gem  into 
the  hands  of  an  indifferent  assistant,  which  is  tantamount  in 
many  instances  to  leaving  the  negative  to  print  itself.  What 
an  analogy  exists  here  between  that  of  planting  and  culti- 
vating ;  that  of  begetting  and  of  educating  !  Do  not  some 
farmers  dibble  a  hole,  insert  the  seed,  and  then  conclude  their 
labor  is  ended  ?  Do  not  some  parents  almost  come  to  the 
same  conclusion  ?  They  both  leave  the  cultivation  and  edu- 
cation of  the  young  germs  to  the  sun,  the  wind,  and  the  wea- 
ther, not  to  Providence ;  for  he  that  believes  in  Providence, 
puts  his  shoulder  to  the  wheel  and  works  for  Providence. 
In  a  manner  quite  analogous,  the  photographer  neglects  the 
execution  of  the  printing  department,  regards  the  operation 
as  secondary,  concludes  that  having  secured  a  good  negative, 
prints  will  grow  from  it  like  potatoes  from  the  seedling. 
This  negligence  must  be  abandoned,  and  more  vigorous  ac- 
tion commenced. 

Positive  printing  is  two-fold,  consisting  in  direct  printing 
by  the  rays  of  the  sun,  and  printing  by  development  or  con- 
tinuation ;  in  the  former  case  the  image  becomes  visible  dur- 
ing the  operation  by  means  of  light  itself ;  in  the  latter  case 
the  impression  made  by  light  is  latent,  and  is  rendered  visi- 
ble afterward  by  chemical  reduction.  The  chemical  mate- 
rials used  in  the  preparation  of  the  paper  for  the  reception 
of  the  image  are,  first,  surface  materials  for  communicating 
a  more  uniform  and  smooth  layer,  such  as  albumen,  gelatine^ 


POSITIVE  PRINTING. 


183 


starch  and  gums  ;  secondly,  substances  that  undergo  some  phy- 
sical or  chemical  change  by  the  agency  of  light,  and  which  are 
mixed  with  the  surface-materials ;  these  are  the  chlorides,  bro- 
mides and  iodides  of  the  various  metals.  Paper,  so  prepared, 
is  sensitized  in  the  dark-room  in  a  bath  of  nitrate  of  silver  ; 
the  chloridized  paper,  when  sensitized,  yields  an  image  by 
the  direct  operation  of  light.  Paper,  prepared  with  the 
other  salts,  receives  an  invisible  impression  of  the  image, 
which  is  made  manifest  in  a  bath  of  gallic  acid  or  some  other 
material,  according  to  the  circumstances  of  the  case.  The 
image  obtained  by  the  direct  agency  of  light  has  a  beautiful 
color,  but  the  picture  is  not  permanent,  for  light  continues 
still  to  act  upon  the  prepared  film,  and  finally  obliterates 
the  image.  The  positive  thus  obtained,  therefore,  has  to  be 
fixed  in  the  same  manner  as  the  collodion  picture,  and  by  one 
of  the  same  fixing  solutions,  hyposulphite  of  soda.  But  the 
color  of  the  image  after  fixation  is  far  from  being  bright  and 
agreeable ;  we  have,  therefore,  to  resort  to  means  before  fix- 
ing, during  fixing  or  afterward,  by  which  the  color  can  be  re- 
stored, or  an  agreeable  color  can  be  communicated.  This 
operation  is  denominated  the  toning  of  the  picture.  The 
chemical  substances  used  m  this  operation  are :  chloride  of 
gold,  and  sometimes  nitrate  of  uranium,  together  with  cer- 
tain accessories  that  modify  the  action  of  these  two  salts, 
such  as  carbonate  of  soda,  carbonate  of  lime,  phosphate  of 
soda,  acetate  of  soda,  chlorinetted  lime,  citrate  of  soda,  etc. 
Direct  positive  printing  will  occupy  our  attention  first.  The 
subject  is  divisible  into  the  following  branches  ;  Description 
of  the  principal  materials  used ;  Preparation  of  the  paper ; 
Sensitizing  of  the  paper  ;  Printing  by  exposure  to  the  sun  ; 
Washing  of  the  prints  ;  Toning  of  the  prints  ;  Fixing  of  the 
prints  ;  Washing  of  the  fixed  prints  ;  Drying  of  the  prints  ; 
Cutting  and  Mounting  of  the  prints. 

Description  of  the  Materials  used  in  Positive  Printing. 

Paper,  suitable  for  photographic  purposes,  must  be  homo- 
geneous throughout,  and  of  a  very  fine  texture.  The  surface 
particularly  must  be  uniform  and  satinized,  free  from  all 
marks  or  specks,  or  chemical  particles  which,  by  decomposi- 
tion afterward,  would  spoil  the  picture.  Such  paper  can  be 
had  of  the  different  photographic  establishments,  from  the 
various  paper-mills  of  America,  England,  France,  Germany, 
etc.  Owing  to  the  different  materials  employed  in  the  sizing 
of  the  paper,  arises  a  difference  in  the  tone  of  the  photogra- 
phic picture  ;  some  sizing  consists  of  starch,  others  of  gela- 
tine. 


184 


POSITIVE  PKINTJNG. 


Albumen, 


This  substance  derives  its  name  from  the  white  of  egg,  of 
which  it  constitutes  the  greatest  quantity.  It  is  found  also, 
in  blood,  in  the  form  of  serum,  (the  fluid  in  which  the 
blood  corpuscles  swim,)  in  the  serum  of  milk,  in  all  serous 
secretions,  etc.  It  exists  in  two  forms,  soluble  and  insoluble. 
When  coagulated,  or  in  the  insoluble  form,  it  constitutes  a 
portion  of  most  of  the  solid  tissues  of  the  animal  frame. 
Solid  albumen  can  be  obtained  by  evaporating  either  the  se- 
rum of  blood,  (the  watery  fluid  which  separates  from  the  clot 
after  coagulation,)  or  the  white  of  an  egg  to  dryness,  at  a 
temperature  not  exceeding  120°.  The  latter  substance  must 
first  be  broken  up  thoroughly,  so  as  to  separate  the  membran- 
ous or  fibrous  material  that  holds  it  together  in  a  compact 
form,  and  then  after  subsidence  the  fluid  portion  is  decanted. 
The  dry  mass  is  a  yellow,  transparent,  tough  and  hard  sub- 
stance, consisting  of  albumen,  with  a  small  quantity  of  the 
saline  substances  that  exist  in  this  material,  and  which  may 
be  separated  by  digestion  in  alcohol  and  ether.  So  dried,  it 
swells  up  when  put  in  water  and  finally  dissolves.  Before  it 
is  dissolved,  ii  may  be  heated  to  a  higher  temperature  than 
the  boiling  point  of  water  before  it  passes  into  the  insoluble 
condition ;  but  when  dissolved  in  water  and  heated  to  a  tem- 
perature between  140°  and  150°,  it  coagulates,  and  becomes 
quite  insoluble  in  water.  Albumen  in  solution  is  precipitated 
by  alcohol,  acids,  metallic  salts,  and  several  organic  bodies, 
such  as  tannic  acid  and  kreosote.  The  precipitates  of  albu- 
men by  metallic  salts  constitute  two  distinct  substances, 
namely,  albumen  with  the  acid,  and  albumen  with  the  oxide, 
of  which  generally  the  former  is  soluble  and  the  latter  insol- 
uble. Pure  albumen  is  supposed  to  be  really  an  insoluble 
substance,  but  rendered  soluble  by  the  alkalies  which  it  con- 
tains ;  for  if  the  white  of  egg,  or  serum  of  blood,  be  dissolved 
in  a  large  quantity  of  pure  water,  and  the  solution  be  exact- 
ly neutralized  by  acetic  acid,  a  flocculent  precipitate  is  ob- 
tained which  is  insoluble  in  pure  water,  but  easily  soluble 
when  the  latter  contains  a  small  quantity  of  caustic  alkali. 
So  obtained  by  precipitation,  it  has  neither  color,  odor,  nor 
taste.    Albumen  contains  in  one  hundred  parts  : 


Carbon, 
Hydrogen, 
Nitrogen, 
Oxygen, 


53.5 
7.0 
15.5 
22.0 
0.4 
1.6 


Phosphorus, 
Sulphur,  .  , 


100.0 


POSITIVE  PRINTING. 


185 


Common  dried  albumen,  not  obtained  by  precipitation,  con- 
tains, in  addition  to  common  salt,  phosphate  of  soda,  and  car- 
bonate of  soda.  It  can  easily  be  shown  that  white  of  egg 
contains  sulphur,  by  boiling  it  in  a  solution  of  caustic  potas- 
sa  and  acetate  of  lead,  when  a  black  precipitate  of  sulphide 
of  lead  will  be  formed.  The  photographic  student  will  also 
observe  that  albumen  contains  the  elements  of  ammonia, 
which  is  generated  during  the  putrefactive  decomposition  01 
this  material.  The  salts  which  it  forms  with  metallic  oxides 
are  denominated  albuminates  ;  and  the  albuminate  of  silver, 
which  is  formed  at  the  same  time  with  the  chloride  of  this 
metal  in  the  albumen  film,  is  instrumental  in  producing  the 
difference  that  exists  between  a  plain  print  and  an  albumen 
print. 

Gelatine. 

This  substance,  if  it  exist  in  nature,  has  never  yet  been  ob- 
tained otherwise  than  by  the  use  of  boiling  water  ;  it  is  sup- 
posed, therefore,  by  some  to  be  a  product  of  the  decomposition 
of  albumen  or  fibrine.  All  membranes,  such  as  the  sldn,  ten- 
dons, cartilage,  hoofs,  and  bones,  yield,  when  boiled  at  a  high 
temperature,  a  solution  which,  on  cooling,  concretes  into  a 
semi-transparent  tremulous  mass.  This  substance  is  gelatine 
or  its  congener  chondrin,  (from  cartilage.)  The  jelly  obtained 
from  boiling  calves'  feet,  common  size,  isinglass,  and  common 
glue  are  familiar  examples  of  gelatine.  Isinglass  (the  dried 
swimming  bladder  of  the  sturgeon)  dissolves  in  water,  and 
yields  a  very  pure  form  of  gelatine.  When  pure  and  dry, 
gelatine  is  colorless  and  transparent ;  it  swells  and  softens  in 
cold  water,  in  which  it  is  very  sparingly  soluble ;  but  in  hot 
water  it  dissolves  very  easily.  Alcohol  and  ether  do  not  dis- 
solve it ;  it  is  precipitated  by  alcohol  from  an  aqueous  solu- 
tion. When  dry  it  can  be  preserved  for  an  indefinite  time 
without  alteration ,  but  in  a  moist  state  it  undergoes  decom- 
position, becomes  acid,  and  ceases  to  gelatinize.  Long-con- 
tinued boiling  produces  the  same  effect.  Some  metallic  salts 
produce  a  flocculent  precipitate  in  solution  of  gelatine,  so 
does  chlorine ;  but  its  most  characteristic  property  is  that  oi 
being  precipitated  from  a  very  dilute  solution  by  means  of 
tannic  acid,  the  only  acid  by  which  it  is  precipitated.  Act- 
ing on  this  principle,  skins  are  converted  into  leather  by  the 
process  called  tanning ;  but  skins  are  not  boiled  in  this  pro- 
cess, and  hence  it  is  supposed  that  gelatine,  after  all,  is  a  na- 
tural product. 

When  gelatine  is  digested  in  strong  sulphuric  acid,  or  in 
caustic  potassa  the  same  decomposition  is  effected.  Ammo- 


186 


POSITIVE  PKINTING. 


nia  is  invariably  one  of  the  products,  and  among  other  pro- 
ducts we  may  count  sugar  of  gelatine  or  glycocine  and  leu- 
cine. 

Dry  gelatine  is  found  to  contain  in  one  hundred  parts : 

Carbon,  50.05 

Hydrogen,  6.47 

Nitrogen,  18.35 

Oxygen,  25.13 

100.00 

Amylaceous  or  Non-Azotized  Substances. 
Starch,  arrow-root,  cellulose,  gum-arabic,  etc.,  belong  to  this 
class  of  bodies.  They  are  found  in  the  vegetable  kingdom 
in  a  free  state,  and  produce  by  slight  changes  in  the  veg- 
etable organization,  a  great  variety  of  substances,  containing 
no  nitrogen,  and  differing  essentially  only  in  the  different  num- 
ber of  equivalents  of  water  with  which  they  are  combined, 
or,  as  far  as  regards  chemical  equivalents,  sometimes  not  dif- 
fering at  all ;  for  starch,  dextrin,  arrow-root,  gum-tragacanth, 
cellulose,  ami  din,  all  contain  the  same  number  of  equivalents 
of  carbon,  hydrogen,  and  oxygen,  and  are  all  resolved  into 
saccharine  substances  by  treatment  with  acids. 

Starch. 

Seeds,  roots,  tubers,  and  stems  of  most  plants  contain  this 
substance  in  the  form  of  very  minute  insoluble  granules.  If 
pumpkins,  potatoes,  or  horse-chestnuts  be  rasped,  and  the 
pulp  be  then  well  washed  on  a  line  sieve,  these  granules 
will  pass  through  the  meshes,  whilst  the  cellular  tissues  will 
be  retained  on  the  sieve.  The  powder  will  finally  subside, 
and  the  fluid  above  it  can  be  poured  off.  This  substance  is 
starch,  which  has  .to  be  washed  several  times,  in  order  to  get 
rid  of  impurities,  and  especially  the  bitter  principle  peculiar 
to  certain  seeds  and  plants.  After  the  white  residue  has  thus 
been  thoroughly  purified,  it  is  dried  at  a  gentle  heat,  by  which 
it  concretes  and  cracks  into  the  form  in  which  it  generally  ex- 
ists in  commerce.  Starch  is  not  only  insoluble  in  water,  but 
also  in  alcohol.  When  examined  in  the  microscope,  these 
granules,  of  an  oblong  shape  generally,  exhibit  concentric 
rings  by  which  the  starch  granule  is  easily  designated  from 
other  powders,  and  frequently  the  granule  of  one  plant  can 
be  distinguished  from  that  of  another,  as,  for  instance,  that 
of  the  potato  from  that  of  arrow-root.  The  latter  substance 
is  the  starch  obtained  from  the  roots  of  the  maranta  arundi- 
?iacea,  growing  in  the  West-Indies.   The  size  of  the  granule 


POSITIVE  PRINTING. 


187 


varies  from  ffa  to  -^jo  parts  of  an  inch  in  diameter.  Each 
granule  is  regarded  as  a  cell  of  concrete  and  insoluble  mate- 
rial, holding  within  a  soluble  pulp.  When  boiled,  the  cells 
are  burst  or  broken  up,  and  the  soluble  part  mixes  with  the 
water  and  forms  a  thick  gelatinous  mass,  called  amidine.  If 
the  solution  of  starch  be  dried  at  a  gentle  heat  and  then  di- 
gested in  cold  water,  the  fluid  portion  can  be  separated  from 
the  insoluble  husks  or  cells,  in  a  colorless,  transparent  form. 
A  thin  solution  of  starch  is  precipitated  by  several  bases,  as 
lime,  baryta,  and  protoxide  of  lead ;  a  large  addition  of  alco- 
hol has  the  same  effect.  Infusion  of  galls  causes  a  yellow 
precipitate  which  dissolves  when  the  solution  is  heated.  The 
best  test  of  the  presence  of  starch  is  free  iodine,  which  pro- 
duces a  beautiful  violet-blue  color  or  precipitate  in  solution 
of  this  substance.  The  blue  color  disappears  on  the  applica- 
tion of  heat,  and  returns  as  the  solution  cools. 

The  substance  called  British  gum  is  simply  starch  that 
has  been  heated  above  240°,  when  the  latter  softens  and  be- 
comes brown  and  soluble  in  cold  water.  If  a  solution  of 
starch  be  boiled  with  a  small  quantity  of  dilute  sulphuric, 
hydrochloric,  or,  in  fact,  almost  any  acid,  it  soon  becomes 
thin  and  is  then  called  dextrine.  The  sulphuric  acid  is  after- 
ward removed  by  adding  chalk  to  saturation,  and  then  by  fil- 
tering and  evaporating  the  filtrate  to  dryness.  The  substance 
thus  obtained  resembles  gum  and  is  soluble  in  cold  water. 
By  continuing  the  action  of  sulphuric  acid  and  the  boiling, 
dextrine  is  converted  into  grape-sugar.  This  conversion  is 
produced  also  in  the  act  of  germination  of  seeds  as  in  malt- 
ing. 

Gum- Arabic. 

This  substance  is  the  spontaneous  exudation  from  the  bark 
of  the  acacia  vera  and  the  acacia  arabica.  In  its  purest  and 
finest  condition,  it  is  in  the  form  of  white  or  slightly  yellow- 
ish concretions,  which  are  soluble  in  cold  water,  forming 
thus  a  viscid,  adhesive  solution.  The  pure  gummy  princi- 
ple, called  arabine,  is  precipitated  by  alcohol  and  by  basic 
acetate  of  lead. 

Chloride  of  Gold. 
Gold  does  not  dissolve  directly  in  hydrochloric  acid,  but 
it  enters  into  combination  very  vigorously  with  moist  chlo- 
rine, or  with  chlorine  in  the  nascent  state.    The  menstruum 
in  which  it  dissolves  is  nitro-hydrochloric  acid. 

Gold.— Symbol,  Au.    Combining  Proportion,  197.    Specific  Gravity,  19.3. 
Protoxide  of  Gold. — Symbol,  Au  0.    Combining  Proportion,  205. 
Teroxide  of  Gold. — Symbol,  Au  03.    Combining  Proportion,  221. 
Terchloride  of  Gold.— Symbol,  Au  Cl3.    Combining  Proportion,  303. 


188 


POSITIVE  PKINTING. 


Gold  dissolves  in  a  mixture  of  one  part  nitric  acid  and 
four  parts  hydrochloric  acid.  In  this  mixture  the  nitric  acid 
becomes  decomposed,  parting  with  oxygen,  which  then  de- 
composes the  hydrochloric  acid  and  combines  with  its  hy- 
drogen to  form  water,  whilst  the  chlorine  in  the  nascent 
state  combines  with  the  gold  in  the  solution.  This  is  after- 
ward evaporated  on  a  water-bath  in  order  to  drive  off  all 
excess  of  acid.  In  this  way  we  obtain  a  red-brown,  de- 
liquescent crystalline  mass  of  the  terchloride.  If  the  heat 
be  too  great,  the  salt  is  decomposed,  chlorine  is  set  at  liber- 
ty, and  a  protochloride  or  metallic  gold  is  left,  according  to 
the  temperature.  The  terchloride  is  very  soluble  in  water, 
ether,  and  alcohol.  The  solution  has  a  yellow  color  and  an 
acid  reaction ;  it  stains  the  skin  purple.  Ether  separates 
this  salt  from  an  aqueous  solution  very  effectually  by  agita- 
tion ;  and  the  mixture  ascends  and  forms  a  layer  on  the  sur- 
face of  the  water,  which  can  easily  be  separated  by  decanta- 
tion,  by  a  syringe,  or  by  allowing  the  water  solution  to  flow 
off  from  a  funnel ;  after  which  the  ether  is  expelled  and  col- 
lected by  distillation. 

Most  of  the  deoxidizing  agents  reduce  terchloride  of  gold, 
such  as  hydrogen,  carbon,  carbonic  acid,  deutoxide  of  nitro- 
gen, sulphurous  acid,  phosphorous  acid,  and  their  salts,  ter- 
chloride of  antimony,  the  proto-salts  of  iron,  many  of  the  me- 
tals, most  organic  substances,  and  oxalic  acid. 

The  crystallized  terchloride  has  a  dark  reddish-brown  color ; 
but  if  it  contains  excess  of  hydrochloric  acid,  it  has  a  bright 
yellow  color  ;  the  solutions  partake  of  the  same  color ;  the 
color,  therefore,  is  a  criterion  of  the  purity  of  this  salt.  A 
strong  solution  of  the  salt  has  a  dark  olive-green  tinge, 
which  becomes  yellow  by  dilution.  This  salt  combines  with 
the  analogous  potassium,  sodium,  and  ammonium  salts,  giv- 
ing rise  to  definite  compounds  of  these  double  salts,  which 
are  very  frequently  sold  in  commerce  for  the  true  terchlo- 
ride.   The  formulas  for  these  three  salts  are  : 

Aurochloride  of  Potassium. — K  CI.  Au  Cl3  +  5  Aq. 
Aurochloride  of  Sodium. — Na  01.  Au  Cl3  +  4  Aq. 
Aurochloride  of  Ammonium. — NH4  CI.  Au  Cl3  +  2  Aq. 

All  these  salts,  as  well  as  the  double  salt  of  gold  and  cal- 
cium, are  used  in  toning.  They  are  formed  by  neutralizing 
the  hydrochloric  acid  in  excess  in  the  terchloride  by  means 
of  the  respective  carbonates  of  the  preceding  metals. 

Refuse  gold  solutions  are  reduced  in  general  by  either 
sulphate  of  the  protoxide  of  iron  or  by  oxalic  acid.  The 
brown  powder  which  subsides  is  well  washed,  first  with 


POSITIVE  PRINTING. 


189 


water,  then  with  boiling  hydrochloric  acid ;  this  is  pure 
gold  in  a  fine  pulverulent  form,  which  can  be  used  for  gild- 
ing and  enameling,  or  for  making  pure  terchloride. 

The  gold  coins  of  the  country  are  alloyed  with  either  sil- 
ver or  copper,  which  can  be  separated  by  various  methods. 
Both  the  silver  and  copper  may  be  removed  at  the  same 
time  by  the  following  means :  melt,  for  instance,  a  gold  dol- 
lar together  with  ten  times  its  weight  of  silver  (ten  five-cent 
pieces)  in  a  crucible  ;  when  melted,  pour  it  out  on  a  clean 
stone,  and  afterward  pass  the  lump  between  a  pair  of  rollers 
so  as  to  reduce  it  to  very  thin  foil.  Digest  the  foil  in  pure 
nitric  acid,  which  will  dissolve  the  copper  and  the  silver,  and 
leave  a  residue  of  a  bright  cinnamon  color.  Wash  this  re- 
sidue, which  is  gold  in  a  very  porous  or  pulverulent  condi- 
tion, and  then  dissolve  it,  as  before  directed,  in  nitro-hydro- 
chloric  acid ;  evaporate  to  dryness,  dissolve,  and  rectify  by 
ether. 

Whenever  silver  is  alloyed  with  gold,  it  is  precipitated 
during  the  solution  in  aqua  regia  as  the  insoluble  chloride, 
which  can  be  removed  by  decantation  of  the  chloride  of  gold. 
The  copper  is  afterward  precipitated  as  the  green  carbonate 
by  adding  carbonate  of  soda  to  the  solution  as  long  as  effer- 
vescence is  produced,  .which  is  separated,  in  like  manner,  by 
decantation. 

If  steel  be  dipped  in  an  ethereal  solution  of  the  terchlo- 
ride of  gold,  it  becomes  covered  with  a  film  of  reduced  gold. 
Dry  gilding  is  performed  by  coating  the  article  with  an 
amalgam  of  gold,  submitting  the  same  to  heat,  so  as  to  drive 
off  the  mercury,  and  then  burnishing  the  gilded  surface. 
An  amalgam  of  gold  consists  of  a  solution  of  gold  foil  to 
saturation.  The  article  is  first  dipped  in  a  solution  of 
nitrate  of  mercury,  and  then  covered  with  amalgam. 

The  gold  solution  for  electro-gilding  is  made  by  dissolving 
to  saturation  the  terchloride  of  gold  in  a  saturated  solution 
of  cyanide  of  potassium ;  this  solution  can  afterward  be  di- 
luted ad  libitum. 

Nitrate  of  Uranium. 
Uranium  is  a  metal  which  is  not  very  abundant ;  in  com- 
bination it  occurs  in  the  mineral  pitch  blende,  as  the  black 
oxide ;  with  silica,  oxide  of  lead  and  oxide  of  iron,  as  uran- 
mica  or  chalcolite,  and  as  uranite  in  combination  with  lime 
and  phosphorus. 

Uranium. — Symbol,  U.    Combining  Proportion,  60. 
Sesquioxide  of  Uranium. — Symbol,  U2  03.    Combining  Proportion,  144. 
Nitrate  of  the  Sesquioxide  of  Uranium. — Symbol,  U2  03,  NO3.  Combining 
Proportion,  198. 


190 


POSITIVE  PRINTING. 


This  salt  is  obtained  directly  from  pitch  blende  by  treat- 
ment with  nitric  acid.  The  ore  is  first  pulverized  and  acted 
upon  by  nitric  acid  ;  and  the  solution  is  then  evaporated  to 
dryness.  The  residue  is  then  washed  with  water,  which 
dissolves  the  nitrate  and  leaves  a  quantity  of  sulphate  and 
arseniate  of  the  sesquioxide  of  iron.  The  liquid  still  con- 
tains salts  of  copper,  lead,  and  arsenic ;  these  are  removed 
by  passing  a  current  of  hydrosulphuric  acid  through  the  so- 
lution, which  precipitates  all  these  metals.  The  solution  de- 
canted or  filtered  from  the  sulphides  of  the  above  metals  is 
evaporated  to  dryness,  and  the  residue  is  again  treated  with 
water,  which  takes  up  the  nitrate  and  leaves  a  residue  of 
sesquioxide  of  iron.  The  solution  is  now  evaporated  and 
crystallized. 

Nitrate  of  uranium  is  a  yellow  salt,  which  is  very  soluble ; 
it  contains  six  equivalents  of  water,  which  by  heat  can  be  ex- 
pelled, and  by  greater  heat  the  salt  is  decomposed.  The  al- 
kaline carbonates  all  produce  yellow  precipitates  with  the 
salts  of  the  sesquioxide ;  whilst  ferrocyanide  of  potassium 
produces  a  red-brown  precipitate.  This  salt  has  been  lat- 
terly used  in  the  toning-bath  along  with  the  terchloride  of 
gold. 

Acetate  of  Soda — Citrate  of  Soda— Phosphate  of  Soda. 

These  three  salts  are  easily  prepared  by  adding  to  each  of 
the  acids,  acetic,  citric,  and  phosphoric,  carbonate  of  soda  as 
long  as  there  is  any  effervescence.  The  solutions  are  then 
evaporated  and  crystallized. 

Acetate  of  Soda.— Symbol,  Na  0,  C4  H3  03  +  6  HO. 
Citrate  of  Soda.— Symbol,  3  Na  0,  C,2  H5  On. 
Phosphate  of  Soda.— Symbol,  2  Na  0,  HO.  P05. 

Carbonate  of  Soda. 
Symbol,  Na  0,  CO2. 
This  salt  is  now  obtained  from  chloride  of  sodium  or  com- 
mon salt.  The  latter  salt  is  first  decomposed  into  sulphate 
of  soda ;  the  sulphate  of  soda  is  next  roasted  with  charcoal, 
by  which  it  is  converted  into  sulphide  of  sodium  /  and  final- 
ly the  latter  substance,  by  roasting  with  powdered  limestone 
and  coal,  is  reduced  to  carbonate  of  soda. 

Carbonate  of  Lime. 
Symbol,  Ca  0,  C02.    Combining  Proportion,  50. 
This  substance  occurs  in  great  abundance,  as  chalk,  marl, 
marble,  and  limestone.    Chalk  is  sufficiently  pure  for  the  pur- 
pose alluded  to.   When  added  to  the  terchloride  of  gold,  car- 


POSITIVE  PRINTING. 


191 


bonic  acid  is  liberated,  and  chloride  of  calcium  formed,  giv- 
ing rise  to  the  double  salt,  aurochloride  of  calcium,  which  is 
to  be  decanted  from  the  insoluble  residue.  This  salt  is 
more  easily  prepared  in  a  definite  condition  than  any  of 
the  preceding  aurochlorides ;  and  on  this  account  its  em- 
ployment in  the  toning-bath  is  more  reliable  and  to  be  re- 
commended. 

Chloride  of  Ammonium. — Symbol,  NH4  CI.    Combining  Proportion,  52. 
Chloride  of  Sodium. — Symbol,  Na  CI.    Combining  Proportion,  58. 
Chloride  of  Potassium. — Symbol,  K  CI.    Combining  Proportion,  74. 
Chloride  of  Barium. — Symbol,  Ba  CI.    Combining  Proportion,  104. 
Chloride  of  Calcium. — Symbol,  Ca  CI.    Combining  Proportion,  63. 

All  these  chlorides  can  be  so  easily  prepared  by  saturating 
hydrochloric  acid  with  their  respective  carbonates  as  long 
as  effervescence  is  produced,  that  it  is  not  necessary  to  de- 
scribe them  separately.  There  is  this  to  be  remarked  about 
them  in  their  application  to  photography,  that  the  same 
quantity  of  either  (a  thing  which  I  need  scarcely  remark) 
will  not  produce  the  same  effect.  Of  those  already  men- 
tioned, the  chloride  of  ammonium  by  weight  requires  to  be 
used  in  the  smallest  quantity,  whilst  the  chloride  of  barium, 
when  just  twice  as  heavy,  is  only  equally  efficacious  in  pro- 
ducing a  given  quantity  of  chloride  of  silver. 

The  iodides  and  bromides,  as  also  gallic  acid,  have  been 
already  described.  We  shall,  therefore,  proceed  to  the  mi- 
nutiae of  the  manipulation  of  positive  printing  by  contact. 


CHAPTEE  XXXL 


MANIPULATION  OF  POSITIVE  PRINTING. 

Preparation  of  Salted  Paper. 

For  sensitizing  paper  and  for  toning,  washing,  and  fixing, 
we  require  either  porcelain  or  gutta-percha  dishes  of  an  ap- 
propriate size.  These  can  be  had  of  the  city  dealers,  of  any 
size  that  may  be  needed ;  those  of  gutta-percha  are  the  best 
for  large  operations.  The  photographic-ware  baths  may  also 
be  used  for  these  purposes,  and  are  to  be  recommended  on 
account  of  their  cheapness. 

There  are  several  kinds  of  paper  in  use,  such  as  Saxony 
paper,  French  paper,  and  English  paper.  There  is  a  differ- 
ence in  the  surface  of  paper,  that  is,  there  is  a  right  side  and 
a.  wrong  side.  The  smooth  or  right  side  is  the  one  which 
receives  the  sensitizing  materials  ;  it  can  easily  be  distin- 
guished from  its  opposite  or  wrong  side.  Salted  paper  may 
be  either  arrow-root  or  albumenized  paper. 

Plain  Salted  Paper. 
Make  a  solution  as  follows  : 

Salting  Solution.    Formula  No.  1. 


Chloride  of  ammonium,  .  .  .  .100  grains. 
Distilled  water,  10  ounces. 

Formula  No.  2. 
Chloride  of  ammonium,  .    .    .    .100  grains. 

Distilled  water, '  10  ounces. 

Gelatine,  10  grains. 

Formula  No.  3. 

Chloride  of  sodium,  40  grains. 

Chloride  of  ammonium,     ...      60  " 

Citrate  of  soda,   100  " 

Gelatine,  10  " 

Distilled  water,  10  ounces. 


Dissolve  the  gelatine  in  warm  water,  then  add  the  solution 
to  the  chloride  and  water,  and  filter  into  the  porcelain  or 
gutta-percha  dish.    The  mixture  in  each  formula  is  filtered 


MANIPULATION"  OF  POSITIVE  PRINTING. 


193 


before  use.  The  object  of  the  citrate  is  to  give  a  slight  ro»^ 
tinge  to  the  middle  tones. 

The  sheets  of  paper  are  now  prepared  ns  follows  : 
Fold  back  each  corner  of  the  sheet  so  as  to  form  a  lip  by 
which  to  hold  it ;  these  lips  are  from  the  smooth  or  satin 
side  backward  to  the  wrong  side.  Then  taking  the  lip  on 
the  right-hand  farther  corner  between  the  first  finger  and 
the  thumb  of  the  right  hand,  and  the  lip  on  the  left-hand 
corner  between  the  thumb  and  the  finger  of  the  left  hand, 
raise  the  sheet,  bend  it  into  a  curve,  and  lower  the  middle 
part  upon  the  surface  of  the  salting  solution ;  now  lower  the 
right  hand  gradually  so  that  the  farther  side  of  the  sheet 
rests  upon  the  fluid  ;  and  then  lower  the  left  hand  in  like 
manner,  until  the  whole  sheet  swims  uniformly  upon  the 
surface.  The  next  thing  is  to  see  that  there  are  no  bubbles 
beneath  the  sheet.  With  a  glass  rod  in  the  right  hand  raise 
the  farthest  right-hand  corner  with  the  left  hand,  and  if  any 
bubble  becomes  visible  break  it  up  with  the  glass  and  moisten 
the  paper  where  the  bubble  existed,  and  proceed  in  this  man- 
ner with  one  half  of  the  sheet.  Next,  holding  the  glass  rod 
in  the  left  hand,  raise  the  nearest  left-hand  corner,  by  the 
lip,  with  the  right  hand,  and  remove  all  bubbles  from  the 
other  half.  When  these  are  all  broken  up,  and  the  paper  is 
moistened  on  the  parts  where  they  existed,  the  sheet  is  low- 
ered on  the  fluid  and  left  there  for  three  minutes.  The  opera- 
tion of  removing  the  bubbles  is  the  work  of  a  moment.  You 
have  to  learn  the  knack  of  floating  the  sheets  on  the  salting 
solution  without  soiling  the  back  of  the  sheet,  that  is,  with- 
out getting  any  of  the  fluid  on  this  side.  If  the  two  sides 
of  the  paper  are  equally  smooth,  that  part  which  is  not  cov- 
ered with  the  salting  solution  is  marked  in  one  corner  with 
a  pencil  or  stamp-mark.  After  the  expiration  of  the  three 
minutes,  each  sheet  is  raised  in  the  following  manner.  The 
lips  will  have  sunk  down  on  the  surface  of  the  fluid  ;  with  the 
glass  rod  in  the  left  hand  raise  the  nearest  right-hand  cor- 
ner, seizing  this  lip  with  the  thumb  and  finger  of  the  right 
hand,  raise  the  sheet  gradually.  Laying  aside  the  rod,  seize 
now  the  nearest  left-hand  lip  with  the  left  hand  and  hold 
the  hands  apart  as  far  as  the  paper  will  permit,  and  the  left 
hand  more  elevated  than  the  right,  allow  the  sheet  to  drain 
into  the  bath.  Now  letting  the  right-hand  corner  go,  with 
a  pin  fix  the  upper  left-hand  corner  to  the  wooden  partition 
or  slip  of  wood  for  this  special  purpose.  If  the  sheets  are 
large,  pin  also  the  upper  right-hand  corner  in  like  manner, 
to  prevent  the  sheet  from  curling  upon  itself  whilst  drying. 
9 


194 


MANIPULATION  OF  POSITIVE  PRINTING. 


Remove  the  accumulating  drops  of  salting  fluid  from  the 
lowest  corner,  and  then  let  the  sheets  dry.  After  this  opera- 
tion the  sheets  are  piled,  with  the  unsalted  sides  downward, 
one  upon  another,  and  a  smooth  board  placed  above  and  be- 
low the  pile,  and  submitted  to  pressure  until  required  for 
use. 

Preparation  of  Albumenized  Paper. 

Albumen  can  be  used  either  pure  or  diluted.  "With  pure 
albumen  the  prints  are  very  brilliant,  but  the  paper  is  not  so 
easily  prepared.  Take,  for  instance,  the  whites  of  twenty 
eggs,  taking  care  to  separate  the  yolk  thoroughly,  and  place 
them  in  a  graduated  measure.  Remove  all  the  germs  with 
a  glass  rod,  and  ascertain  the  number  of  ounces.  Afterward 
pour  the  crude  albumen  into  a  clean  basin,  and  add  for  every 
ounce  ten  grains  of  chloride  of  ammonium  dissolved  in  the 
least  quantity  of  distilled  water.  Beat  the  mixture  into  a 
thick,  white  froth  by  means  of  an  egg-beater,  and  allow  it  to 
stand  for  ten  minutes  ;  then  remove  the  froth  with  a  fork, 
and  throw  it  upon  a  clean  hair-sieve.  Proceed  in  like  man- 
ner with  the  residual  fluid,  until  it  has  been  completely  con- 
verted into  froth  and  strained  through  the  siev&  Now  leave 
the  albumen  to  stand  for  a  day  or  so,  well  covered  up  from 
dust ;  after  which  filter  through  a  piece  of  sponge,  and  again 
allow  the  mixture  to  settle  for  a  couple  of  days,  and  then 
pour  off  the  supernatant  liquid  portion  from  the  settlings 
into  the  porcelain  or  gutta-percha  dish  for  use. 

The  paper,  as  usual,  must  be  of  the  finest  quality,  and 
marked  or  stamped  on  the  back,  before  floating.  Much 
more  care  is  required  in  the  successful  management  of  laying 
the  paper  on  the  salted  albumen  than  upon  the  plain  salting 
solution,  for  bubbles  are  more  likely  to  be  formed,  and  are 
less  easily  removed  than  in  the  former  preparation.  Besides 
this,  if  the  paper  be  dry,  and  the  weather  also  very  dry,  the 
albumen  does  not  attach  itself  easily  to  the  paper,  and  in  this 
case,  although  a  sheet  has  been  thoroughly  floated,  and  with- 
out bubbles,  the  upper  part  of  the  sheet,  when  hung  up,  al- 
lows the  albumen  to  flow  off,  so  that  the  film  on  the  upper 
part  is  much  thinner  than  on  the  lower  part,  and  a  number 
of  irregular  marks  and  curves  are  apt  to  be  formed  on  the 
lower  part.  To  obviate  this,  the  sheet  is  suspended  by  its 
broadside,  by  which  the  distance  between  the  upper  and 
lower  side  is  the  least  possible.  The  time  of  salting  in  this 
bath  is  from  two  minutes  and  a  half  to  three  minutes.  Of 
course  in  all  cases  the  time  has  to  be  reckoned  from  the  mo- 


MANIPULATION"  OF  POSITIVE  PRINTING.  195 


merit  the  sheet  lies  uniformly  and  without  bubbles  on  the 
surface  of  the  solution. 

In  every  operation  of  this  nature  it  is  well  to  have  sys- 
tematic arrangements.  For  this  purpose  I  recommend  the 
photographer  to  proceed  as  follows  in  the  preparation  of  his 
drying-chamber.  On  the  side  of  the  room,  behind  the  salting 
solution,  and  at  an  elevation  of  the  eyes  of  the  individual, 
screw  on  a  slip  of  wood  a  couple  of  inches  wide  and  the 
length  of  the  room.  Supposing  then  the  sheets  are  twenty- 
two  inches  long,  then  bore  two  holes  twenty-one  inches  apart 
through  the  slip  of  wood ;  into  the  apertures  insert  corks,  fitting 
firmly,  and  projecting  about  half  an  inch  from  the  surface  of 
the  wood.  Into  the  center  of  each  of  these  corks  insert  the 
eye  end  of  a  steel  needle  inclined  slightly  upward.  The 
sheets  when  raised  by  the  two  interior  corners,  and  after 
draining,  are  hooked  by  the  two  upper  corners  upon  the  pro- 
jecting needles,  whi«h,  before  their  insertion  into  the  corks, 
have  to  be  varnished  to  prevent  rusting  and  other  troubles. 
When  several  rows  of  sheets  have  to  be  dried  consenta- 
neously the  uppermost  slip  of  wood  must  be  the  thickest,  as, 
for  instance,  three  inches,  if  there  are  three  rows,  one  over 
the  other;  the  second,  two  inches  ;  and  the  last,  one  inch  thick. 

In  proportion  as  the  albumen  accumulates  on  the  lower 
border,  it  is  removed  with  bibulous  paper,  until  the  papers 
finally  are  dry.  They  are  then  taken  down  and  planished 
between  rollers  or  otherwise,  and  piled  away. 

Preparation  of  Arrow-Boot  Paper. 
Cut  out  a  board  a  trifle  less  in  length  and  width  than  the 
sheet  of  paper ;  fix  a  sheet  at  a  time  by  a  pin  at  each  cor- 
ner of  each  edge,  folding  the  edges  of  the  paper  down  over 
the  edges  of  the  board.  Then,  with  a  very  fine,  soft  and 
moist  sponge  cover  it  over  smoothly,  longitudinally  and  lat- 
erally with  the  following  salting  mixture : 

Formula. 

Chloride  of  sodium,  (common  salt,)        5  drachms. 

Citric  acid,  4  grains. 

Distilled  water,  19  ounces. 

Dissolve  and  filter.  Then  add  four  drachms  of  arrow-root, 
rubbed  with  cold  water  into  a  cream,  so  that  all  lumps  have 
been  thoroughly  broken  up  and  saturated.  Boil  the  mixture 
in  a  glass  or  porcelain  dish,  taking  care  to  stir  it  all  the 
while.  When  it  is  cold,  and  the  scum  has  been  removed,  it  is 
ready  for  application  with  the  sponge.  By  means  of  a  glass 
trianglt  jv  glass  rod,  all  ridges  or  asperities  may  be  removed, 


196 


MANIPULATION  OF  POSITIVE  PEINTING. 


and  the  paper  is  then  suspended,  as  before  directed  for  albu- 
men-paper. Arrow-root  paper  is  well  adapted  for  large  por- 
traits, and  even  for  large  landscapes ;  for  smaller  pictures, 
where  more  fineness  of  grain  and  sharpness  are  required,  al- 
bumenized  paper  is  by  far  the  best.  All  the  papers,  pre- 
pared as  directed,  will  keep,  but  they  are  best  when  fresh. 

Sensitizing  Path. 
The  preparations  for  sensitizing  are  divided  into  two  class- 
es, one  containing  essentially  nitrate  of  silver,  and  the  other 
ammonio-nitrate  of  silver ;  these  are  subdivided  by  differ- 
ences in  the  strength.  The  ammonio-nitrate  of  silver  solu- 
tion is  certainly  much  more  sensitive  than  the  plain  silver 
bath ;  the  great  drawback  has  been  the  blackening  of  the  so- 
lution by  use,  for  which  several  remedies  have  been  proposed. 
Whichever  bath  is  used,  its  strength  has  to  be  maintained  at 
its  original  point  by  the  addition  of  fresh  silver  every  time  it 
is  used,  for  the  bath  soon  becomes  impoverished  by  the  float- 
ing of  paper  for  printing.  The  sensitizing  solution  must  al- 
ways be  slightly  acid,  in  order  that  the  whites  may  be  thor- 
oughly preserved. 

Formula  for  the  Plain  Silver  Solution. 

Nitrate  of  silver,  2  ounces. 

Kain-water,  12  ounces. 

Nitric  acid,  2  to  3  drops. 

The  paper  to  be  sensitized  in  this  bath  is  prepared  exactly 
in  the  same  manner  as  for  floating  in  the  salting  solution ; 
the  corners  are  turned  back,  and  then,  seizing  two  opposite 
corners  and  bending  the  paper  into  a  curve  with  the  middle 
and  salted  part  downward,  it  is  lowered  into  contact  with 
the  fluid,  while  first  one  end  is  gradually  let  down  and  then  the 
other,  taking  care  afterward  to  remove  all  bubbles  with  the 
glass  rod,  by  first  raising  one  corner  and  then  the  other. 
Previous  to  use,  the  bath  ought  to  be  always  filtered  from  in- 
numerable little  particles  and  scum  that  accumulate  on  its 
surface.  By  means  of  an  argentometer  the  strength  of  the 
bath  can  easily  be  maintained  at  a  given  point,  namely,  at 
about  70  grains  to  the  ounce  of  water;  and  by  the  applica- 
tion of  test  paper,  it  can  be  ascertained  whether  it  be  acid  or 
alkaline,  and  thus  corrected.  I  will  repeat,  the  bath  must  be 
Slightly  acid. 

Filtered  every  time  it  is  used. 
Its  strength  maintained  at  70  grains  to  the  ounce. 
The  papers  are  floated  on  the  fluid  for  five  minutes,  then 


MANIPULATION  OF  POSITIVE  PRINTING. 


197 


raised,  allowed  to  drain,  and  hung  up  on  varnished  steel 
needles  inserted  into  corks  in  a  line  over  the  gutter  alluded 
to  in  a  former  part  of  this  work ;  or  if  such  a  contrivance  be 
wanting,  the  silver  solution  is  removed  from  the  pendent  cor- 
ners by  blotting-paper,  which  is  afterward  thrown  aside  on  a 
special  heap  for  reduction.  The  bath  by  use  will  become  discol- 
ored; in  such  a  case,  throw  in  a  small  quantity  of  solution  of 
common  salt  by  degrees  and  shake  well.  This  will  remedy 
the  evil  after  filtration,  but  it  removes  also  a  considerable 
quantity  of  silver,  which  has  to  be  replenished.  The  black 
residue,  together  with  the  precipitated  chloride  of  silver,  is 
preserved  with  all  other  refuse  silver  for  reduction. 

Formula  for  the  Ammonio- Nitrate  Silver  Solution. 


Dissolve  the  silver  in  six  ounces  of  water ;  then  separate 
two  ounces  of  the  solution,  and  add  ammonia  to  it,  until  the 
precipitate  of  oxide  of  silver  first  formed  is  redissolved.  This 
solution  is  then  mixed  with  the  alcohol,  and  the  remaining 
silver  solution  and  water.  By  the  addition  of  ammonia  de- 
composition takes  place,  oxide  of  silver  of  a  brown  color  is 
thrown  down,  and  nitrate  of  ammonia  is  formed ;  an  addi- 
tional quantity  of  ammonia  then  dissolves  the  oxide,  so  that 
the  solution  contains  nitrate  of  ammonia  and  solution  ot 
oxide  of  silver  in  ammonia.  When  this  part  is  thrown  into 
the  remaining  solutions,  oxide  of  silver  is  again  precipitated  ; 
the  final  solution  therefore  contains  free  oxide  of  silver,  and 
solution  of  oxide  of  silver  in  nitrate  of  ammonia  and  alcohol. 
The  alcohol  prevents  the  solution  of  the  albuminous  film  and 
discoloration  probably. 

The  papers  are  floated  in  this  bath  not  more  than  a  minute ; 
half  a  minute  I  find  in  most  cases  to  be  sufficient.  But  there 
is  this  caution  to  be  observed :  if  the  papers  when  removed 
from  the  bath  appear  streaked  with  oil,  it  is  well  to  rub  the 
fluid  gently  over  the  whole  surface  with  a  tuft  of  cotton  wool. 
The  bath  can  be  filtered,  but  in  that  case  the  same  filter  has 
to  be  used  over  and  over  again,  because  the  oxide  of  silver 
is  gradually  taken  up  and  dissolved  by  the  ammonia  liberated 
during  the  operation.  I  prefer,  however,  not  to  filter  the 
bath,  but  after  use  to  keep  it  in  the  stock-bottle,  together 
with  the  residue  of  oxide  of  silver.  When  about  to  use  it, 
it  is  carefully  decanted  into  the  dish,  and  after ,  settling,  a 
small  sheet  of  paper  is  drawn  over  the  surface  to  remove  any 


Nitrate  of  silver, 
Rain-water,  . 
Alcohol,     .  . 


2  ounces. 
8  ounces. 
1  ounce. 


198 


MANIPULATION  OF  POSITIVE  PBINTING. 


particles  that  might  be  left.  The  strength  of  this  bath,  like 
any  other,  has  to  be  kept  up  by  the  addition  of  crystals  of 
nitrate  of  silver  ;  fresh  alcohol  and  ammonia  are  added  from 
time  to  time.  The  albuminous  film  is  not  injured  by  this 
solution  ;  the  time  of  floating  is  much  shortened,  and  although 
the  strength  of  the  solution  is  higher  than  that  of  the  pre- 
ceding, no  more  silver  is  wasted  or  consumed  in  the  opera- 
tion, because  the  picture  is  maintained  on  the  surface  of  the 
film,  owing  either  to  the  diminution  of  the  time  of  floating, 
or  to  the  induration  or  coagulation  of  the  albumen,  or  to  its 
dryness  and  consequent  impermeability  in  so  short  a  time. 

Faminating  Process. 

The  advantages  of  the  ammonio-nitrate  sensitizing  solution 
are  attained  by  subjecting  the  sheets  of  paper,  already  sensi- 
tized by  the  plain-nitrate  of  silver  solution,  to  the  fumes  of 
ammonia.  The  modus  operandi  is  as  follows  :  Float  the  pa- 
pers for  four  or  five  minutes  in  the  first  bath,  containing  from 
sixty  to  seventy  grains  of  nitrate  of  silver  to  the  ounce  of 
water,  and  allow  them  to  dry  as  usual.  This  is  the  first  part 
of  the  process. 

Next  prepare  the  fuminating  box  or  chamber.  Where 
the  quantity  of  work  to  be  done  is  not  very  extensive,  a  box 
three  feet  long,  two  feet  wide  and  two  feet  deep  is  first  con- 
structed. On  either  side  and  five  inches  from  the  top  a  piece 
is  cut  out,  leaving  the  two  ends  projecting  five  inches  above 
the  two  sides.  Construct  next  on  either  side  a  shallow  box 
of  the  same  length  as  the  original  one,  five  inches  deep,  and 
two  feet  wide,  and  having  only  three  sides.  These  are  fast- 
ened by  screws  to  the  large  and  middle  box,  in  such  a  man- 
ner that  the  open  side  fits  exactly  where  the  piece  has  been 
cut  out,  forming  as  it  were  two  shelves.  By  means  of  trian- 
gular supj)orts  these  shelves  are  held  in  a  firm  and  horizon- 
tal position,  and  give  an  appearance  to  the  box,  when  regarded 
from  the  end,  of  the  letter  T.  On  each  end  of  the  deep  box, 
as  well  as  on  each  side,  on  a  level  Avith  the  lateral  shelves, 
screw  on  four  narrow  slips  of  inch  staff,  on  which  can  rest  a 
board  three  feet  long  and  two  feet  wide ;  this  board,  there- 
fore, in  its  place  covers  the  middle  box  like  a  lid.  When  it 
is  in  its  place,  screw  down  a  small  piece  of  wood  on  either 
end  of  one  side,  so  that  it  can  not  slide  too  far.  This  lid  has 
a  sliding  motion  by  means  of  an  iron  rod  in  the  middle  of  one 
side,  lying  horizontally,  and  passing  through  an  aperture  in 
the  side  of  one  of  the  shelves,  so  that  it  maybe  made  to  close 
the  top  of  the  box  or  open  it  when  required.    On  the  top  of 


MANIPULATION  OF  POSITIVE  PEINTING. 


190 


this  T-shaped  cavity,  there  are  three  doors,  each  three  feet 
long  and  one  foot  ten  inches  wide,  opening  by  hinges  as  fol- 
lows :  At  a  distance  of  one  foot  ten  inches  from  either  side  on 
the  top  of  this  cavity  screw  on  a  slip  of  wood  two  inches 
wide;  to  these  slips  the  hinges  are  all  fixed,  so  that  each 
lateral  door  opens  toward  the  middle,  and  lies  wThen  open 
upon  the  middle  door ;  whereas  the  middle  door  opens  to- 
ward one  side  and  lies  upon  the  side  door.  It  is  intended 
that  one  door  alone  is  to  be  opened  at  a  time.  The  wood  of 
which  these  doors  are  constructed  must  be  soft,  so  as  to  al- 
low the  insertion  of  small  tacks  or  pins.  This  is  the  fumin- 
ating  apparatus. 

The  sensitized  dried  sheets  or  pieces  of  paper  are  fixed 
upon  the  inside  of  each  door  by  sticking  a  pin  obliquely  into 
each  corner,  with  the  albumenized  surface  downward  when 
the  door  is  shut.  At  the  bottom  of  the  deep  box  place  a 
plate,  containing  a  drachm  or  more  of  ammonia.  In  winter  a 
pan  of  warm  sand  may  be  introduced,  with  the  plate  over 
this  in  order  to  increase  the  evaporation.  The  sliding  door 
all  this  while  is  open.  When  each  door  is  covered  with 
sheets,  or  with  as  many  as  are  required,  close  them.  It  is 
evident  that  the  fumes  of  the  ammonia  will  soon  fill  the 
whole  of  the  interior,  and  will  thus  come  in  contact  with  the 
surface  of  the  silvered  paper  and  produce  a  decomposition  of 
the  nitrate  of  silver  into  oxide  of  silver  and  nitrate  of  ammo- 
nia. After  the  paper  has  been  exposed  for  about  ten  min- 
utes, the  sliding  door  is  closed  by  pushing  it  forward  with 
the  iron  rod  until  it  juts  against  the  small  pieces  of  wood  on 
either  end  of  the  opposite  shelf.  By  this  means  the  fumes 
of  ammonia  in  the  body  of  the  fuminator  are  excluded  from 
the  air,  and  only  that  portion  escapes  which  lies  on  the  shelves. 
The  fuminated  papers  are  then  taken  out  and  pinned  by  one 
corner  on  the  corks,  in  order  that  all  superfluous  ammonia 
may  escape,  when  they  will  be  ready  for  printing.  It  has 
been  asserted  that  there  is  a  great  saving  of  silver  by  this 
process ;  that  the  film  is  much  more  sensitive  to  light,  and 
consequently  the  time  of  printing  is  shortened,  and  that  the 
tones  are  more  brilliant. 


CHAPTEK  XXXIL 


THE  PRINTING  OF  SENSITIZED  PAPER. 

The  operation  of  printing  is  performed  by  the  direct  rays 
of  the  sun  or  by  diffused  light.  Frames  of  various  sizes  are 
to  be  had  of  the  dealers  for  this  special  purpose.  These  are 
oblong  dishes,  about  two  inches  deep,  with  a  pane  of  plate 
glass  for  the  bottom,  lying  upon  a  ledge  loosely.  Upon  this 
the  negative  is  placed,  collodion  side  upward,  and  over  the 
negative  the  sensitized  paper,  albumen  side  downward.  A 
piece  of  chamois  leather,  soft  cloth  or  Canton  flannel  of  the 
size  of  the  pane  of  glass  is  placed  over  the  paper  carefully,  so 
as  to  keep  it  in  its  position  directly  over  the  negative,  and  to 
form  a  sort  of  cushion  when  the  folding  doors,  that  come 
next,  are  fixed  in  their  place.  There  is  quite  a  knack  in  ad- 
justing the  leather  so  as  not  to  produce  any  friction  upon  the 
negative,  which  would  certainly  injure  if  it  were  not  var- 
nished. The  negative  lies  as  near  the  middle  of  the  pres- 
sure frame  as  can  be,  and  in  the  same  direction  as  to  length. 
The  folding  doors  are  two  thin  flaps  of  wood  joined  by  hinges 
in  the  middle,  equal  in  size  together,  and  lying  horizontally 
to  the  pane  of  glass.  This  door  is  adjusted  in  its  place  over 
the  cloth  or  leather  in  the  following  manner.  Whilst  the 
outstretched  fingers  of  the  left  hand  are  holding  the  paper 
and  cloth  in  their  places,  without  the  slightest  friction,  the 
nearer  flap  is  put  in  its  place  and  held  down  by  a  gentle 
pressure,  whilst  the  left  hand  now  relinquishes  its  hold  and 
closes  down  the  other  flap.  By  means  of  strips  of  wood,  an 
inch  and  a  half  wide,  stretching  across  the  frame  and  fixed 
on  hinges  on  one  side  of  the  printing  frame,  and  supplied 
with  metallic  springs  beneath,  each  flap  is  pressed  down  and 
held  in  its  place  by  means  of  a  hook  on  the  other  side.  By 
such  an  arrangement  it  is  evident  that  each  folding  door  is 
independent  of  its  neighbor,  and  by  opening  it  the  cloth 
over  one  half  of  the  negative  can  be  thrown  back,  the  picture 
can  be  raised  and  examined,  and  again  replaced  without  dis- 
turbing the  relative  position  of  the  paper  and  negative.  So 


THE  PRINTING  OF  SENSITIZED  PAPEK. 


201 


arranged,  the  printing  frame  is  now  exposed  to  the  snn,  by 
rearing  it  on  a  shelf  at  the  outside  of  the  window  right  in 
front  of  this  orb.  The  color  of  the  paper  will  soon  begin  to 
change,  and  soon  the  whole  picture  will  be  apparent.  Some 
negatives  produce  the  best  prints  when  exposed  to  a  very 
powerful  light ;  others  on  the  contrary  require  to  be  printed^ 
slowly.  A  negative  which  is  very  dense  will  yield  the  best  p 
effect  by  exposing  the  frame  to  diffused  light ;  whereas  a  very  / 

thin  negative  may  be  exposed  to  the  full  blaze  of  the  sun,  iu,  

order  to  be  printed  very  quickly.    The  best  prints  are  ob- 
tained from  negatives  that  are  neither  too  dense  nor  too  thin.  

The  frame  is  taken  into  a  shaded  corner  of  the  room  from 
time  to  time,  and  one  end  of  the  print  is  examined  in  order 
to  ascertain  the  progress  of  the  operation.  If  the  lights  are 
still  white,  and  the  shades  not  yet  bronzed  in  the  slightest 
degree,  the  print  is  not  yet  finished.  As  a  rule  it  may  be 
concluded  that  this  operation  is  complete  when  either  the 
lights  have  become  slightly  tinged  by  reduction,  or  when 
bronzing  is  beginning  to  appear  in  any  part  of  the  shadows. 
In  this  case,  take  in  the  frame,  and  placing  it  on  a  table  or 
shelf,  remove  the  folding  doors,  then  the  cloth,  and  finally 
the  print.  Be  careful  not  to  expose  the  print  to  a  strong 
light,  otherwise  the  whites  will  be  injured.  Place  it  between  • 
the  leaves  of  a  book  or  in  a  drawer  in  the  dark-room,  until  a 
sufficient  quantity  has  accumulated  for  the  next  operation. 
An  experienced  printer  will  be  able  to  obtain  satisfactory  re- 
sults as  far  as  circumstances  will  permit;  but  it  is  utterly  im- 
possible to  force  an  inferior  negative  to  yield  a  superior  print ; 
a  certain  relation,  a  certain  happy  relation,  (a  remark  that  I 
have  so  many  times  repeated,  but  not  too  often,)  must  exist 
between  lights,  middle  tones  and.  shades,  with  a  given  den- 
sity of  the  latter  in  order  to  secure  normal  prints  ;  and  where 
this  exists,  it  is  the  fault  of  the  printer  if  he  does  not  arrive 
at  the  maximum  result  of  perfection. 

Toning  of  the  Prints. 
In  the  dark-room,  illumined  by  the  yellow  light  of  a  lamp, 
or  by  that  which  passes  through  the  orange-yellow  non-ac- 
tinic glass,  examine  the  points  separately,  rejecting  each  in 
which  there  is  a  decided  failure,  and  cut  off  all  extraneous 
parts  that  are  certainly  not  required  when  mounted,  allow- 
ing, of  course,  always  sufficient  margin  for  the  final  trimming. 
Next  throw  each  print  separately  into  a  pail  or  tub  of  water, 
taking  care  that  its  surface  comes  in  contact  with  the  water, 
without  the  intervention  of  bubbles.  Keep  the  prints  in  mo- 
9* 


202  THE  PRINTING  OF  SENSITIZED  PAPER. 


lion  by  turning  them  over  and  over  again  for  the  space  of 
five  minutes,  and  afterward  take  them  out  separately  and  im- 
merse them  in  another  tub  of  water  in  the  same  manner  as 
before.  The  water  from  the  first  pail  is  poured  into  a  large 
barrel  or  tank  kept  for  this  special  purpose.  Move  the  prints 
about  as  before  for  five  minutes,  and  then  proceed  to  the 
third  pail  in  like  manner.  The  water  from  the  three  pails  is 
poured  into  the  tank,  and  a  tea-spoonful  of  common  salt  is 
added  and  dissolved  by  agitation  with  a  wooden  stirrer ;  af- 
ter the  subsidence  of  the  deposit  of  chloride  of  silver,  the  ref- 
use water  is  allowed  to  flow  off  into  the  sink  by  a  stop-cock 
inserted  within  a  couple  of  inches  from  the  bottom  of  the 
tank. 

Formula  No  1.  For  the  Toning  Solution. 

Chloride  of  gold,  (pure,)  '1  grain. 

Distilled  water,  8  ounces. 

Carbonate  of  soda  to  neutralize  the  acidity. 
Alcohol,  2  drachms. 

Formula  No.  2. 

Double  chloride  of  gold  and  potassium,  2  grains. 

Distilled  water,  3  ounces. 

Carbonate  of  soda,  3-5  grains. 

Formula  No.  3. 

Chloride  of  gold,  1  grain. 

Distilled  water,  8  ounces. 

Chalk  to  neutralize  the  acidity. 

Chlorinetted  lime,  5  grains. 

Alcohol,  2  drachms. 

Formula  No.  4.    Gold  and  Uranium. 

(  Chloride  of  gold,  (pure,)    ...  1  grain. 

No,  1.      •<  Distilled  water,    4  ounces. 

(  Chalk  to  neutralize  the  acidity.  )    Filter  each 

C  Nitrate  of  uranium,      ....  1  grain.   )  and  then  mix. 

No.  2.      <  Distilled  water,   4  ounces. 

(  Chalk  to  neutralize  the  acidity. 

Formida  No.  5. 

Chloride  of  gold,   2  grains. 

Distilled  water,  8  ounces. 

Phosphate  of  soda,  100  grains. 

Neutralize  with  chalk. 

Formula  Jfo.  6. 

Chloride  of  gold,  (pure,)    .    .    2  grains. 

Distilled  water,   4  ounces. 

No.  1.     -{  Carbonate  of  soda  to  neutralize  the  acidity, 
Phosphate  of  soda,  ....    2  grains. 

Acetate  of  soda,  2  grains. 

(  Nitrate  of  uranium,  ....    2  grains. 
No.  2.     <  Distilled  water,      .    .    .    .    .  4  ounces. 
(  Chalk  to  neutralize  the  acidity. 


Filter  the  latter 
and  mix. 


THE  PKINTING  OF  SENSITIZED  PAPER. 


203 


The  acidity  of  any  of  tlie  above  solutions  is  neutralized  as  fol- 
lows :  In  the  first  place  throw  into  the  solution  a  piece  of  blue 
litmus  paper  of  the  size  of  a  ten-cent  piece,  its  color  will  be 
turned  red  ;  now  throw  in  either  carbonate  of  soda  or  carbon- 
ate of  lime  until .  the  blue  color  is  restored.  Carbonate  of 
lime  (chalk)  has  this  advantage  over  carbonate  cf  soda,  it 
can  be  used  wuthout  litmus  paper,  taking  care  only  to  throw 
in  a  superabundance,  which  does  no  harm,  and  can  afterward 
be  removed  by  filtration.  I  prefer  preparing  the  double  chlo- 
ride of  gold  and  calcium  beforehand,  and  in  quantity  in  a 
concentrated  liquid  form.  In  such  a  condition  a  few  drops 
can  be  added  to  the  toning  bath  in  a  moment,  whenever  it 
is  found  that  the  toning  does  not  commence  or  proceed 
satisfactorily. 

Pure  chloride  of  gold  is  a  deliquescent  salt,  is  not  easily 
crystallized,  and  when  crystallized  is  not  easily  retained  in 
this  form.  Its  color  is  of  a  deep  reddish  color.  But  the 
chloride  of  gold,  sold  as  such,  is  of  a  yellowish  color,  in  a 
dry  crystalline  condition,  and  is  not  deliquescent ;  it  is  there- 
fore not  pure  ;  it  is  probably  in  most  cases  a  double  chloride, 
either  of  gold  and  potassium,  or  of  gold  and  sodium.  These 
double  salts  are  used  in  toning,  as  recommended  in  the  above 
formulas  ;  but  it  must  be  remembered,  that  in  buying  such  an 
article,  double  the  quantity  will  be  required,  and  of  course 
you  have  to  pay  the  price  of  gold  for  the  soda  or  potassa  in 
the  mixture,  which  is  poor  economy. 

With  any  of  the  preceding  formulas  baths  may  be  formed 
which  will  produce  rich  tones.  Formula  No.  5  admits  the 
substitution  of  citrate  of  soda,  or  acetate  of  soda  for  the 
phosphate.  The  first  is  the  simplest,  and  I  think  the  most 
rational;  probably  the  third  will  please  many;  its  tone. is 
more  of  a  sepia.  The  aim  of  the  citrate,  acetate,  and  phos- 
phate is  to  produce  a  purple  tone.  The  uranium  bath  pro- 
duces a  rich  tone,  still  I  do  not  think  it  superior  to  the  sim- 
plest alkaline  gold  bath.  Use  the  bath  slightly  warm,  that 
is,  at  a  temperature  of  90°  or  100°.  Before  the  prints  are  in- 
troduced into  the  toning  bath,  pass  them  separately  through 
hot  water.  Let  the  bath  be  sufficiently  large  to  accommo- 
date a  number  of  prints  side  by  side ;  turn  them  over  contin- 
ually ;  keep  them  in  motion.  The  tone  of  the  prints  soon 
begins  to  change  ;  before  it  becomes  of  a  slate  blue,  take  each 
print  out,  wash  in  hot  water,  and  immerse  in  the  fixing  bath. 


Fixing  Solution. 


Hyposulphite  of  soda, 

Water,  

Alcohol,  .... 


204 


THE  FEINTING  OF  SENSITIZED  PAPER. 


The  first  effect  of  the  to»ing  bath  is  to  change  the  color  to 
a  reddish  line,  and  then  finally  back  again.  Move  the  prints 
about  in  this  bath  continually,  and  keep  them  in  until  the 
whites  are  perfectly  clear  when  viewed  by  transmitted  light, 
and  the  tone  has  been  restored.  Where  the  printing  has 
been  w<jll  performed,  supposing  the  contrast  in  the  negative 
to  be  right,  the  color  of  the  deep  shades  is  but  very  little 
changed  in  the  fixing  solution,  and  very  soon  returns  to  the 
proper  tone.  If  the  whites  are  full  of  gray  spots  when  the 
prints  are  placed  between  the  light  and  the  eyes,  it  is  a  sign 
that  the  fixing  is  incomplete,  and  probably  too  that  the  prints 
during  the  washing  and  the  toning  have  been  too  much  ex- 
posed to  a  strong  light.  All  operations,  until  the  fixing  is 
complete,  ought  to  be  performed  in  a  room  lighted  by  non- 
actinic  rays.  When  the  tone  of  the  picture  and  the  transpar- 
ency of  the  whites  are  satisfactory,  remove  the  print  from 
the  fixing  bath  and  immerse  it  in  a  tub  of  water.  Do  so  with 
all  of  them,  until  the  fixing  operation  is  complete.  The  prints 
are  now  kept  in  motion  for  a  few  minutes  in  the  water,  in 
order  to  remove  as  much  as  possible  of  the  fixing  solution 
from  their  surface.  They  are  then  taken  out  and  allowed  to 
drain,  and  finally  immersed  in  another  tub  of  clean  water, 
where  they  remain  for  a  number  of  hours,  taking  care  to 
move  them  about,  and  to  turn  them  over  frequently.  The 
water  in  the  washing  operation  can  not  be  changed  too  fre- 
quently ;  in  fact,  it  is  by  far  the  most  desirable  plan  to  have  an 
arrangement  by  which  the  prints -can  be  subjected  to  a  run- 
ning stream  of  water,  which  can  easily  be  made  in  large  cities 
supplied  with  w^ater  works. 

The  apparatus  for  this  purpose  is  adjusted  on  pivots  so  as 
to  rise  and  fall  like  the  beam  of  a  pair  of  scales,  and  it  is  put 
in  motion  by  the  weight  of  the  water  itself.  It  consists,  in 
the  first  place,  of  a  trough  of  wood  of  any  given  appropriate 
length,  as,  for  instance,  three  feet ;  its  breadth  may  be  one 
foot,  and  its  height  the  same.  It  is  divided  into  two  com- 
partments in  the  middle,  and  supported  on  pivots  in  .the 
middle  of  the  base-board  about  six  inches  above  the  table  or 
shelf  on  which  it  rests ;  by  this  means  it  has  an  oscillating 
motion  or  play  of  about  twelve  inches  at  either  end,  like  a 
see-saw.  This  trough  is  placed  so  that  the  middle  division 
is,  when  horizontal,  immediately  below  the  stop-cock;  but 
when  one  is  down  and  filled  with  water,  and  the  other  up 
and  empty,  it  is  evident  that  if  the  stop-cock  be  open,  the 
water  will  flow  into  the  empty  compartment  until  this  sinks, 
which  it  will  do  when  the  other  is  empty.    Each  compart- 


THE  FEINTING  OF  SENSITIZED  PAPER. 


205 


merit  is  supplied  with  a  syphon,  whose  arch  reaches  to  a  plane 
nearly  level  with  the  top  ;  the  calibre  of  this  syphon  is  some- 
what greater  than  that  of  the  ingress  pipe  furnished  with  the 
stop-cock.  Now  when  either  end  becomes  filled  with  water, 
the  latter  will  rise  higher  than  the  arch  of  the  syphon,  which 
will  then  be  rilled  with  water.  The  longer  arm  of  the  syphon 
passes  through  the  end  of  each  compartment  and  discharges 
the  water  from  its  corresponding  end  quicker  than  the  water 
is  supplied  to  the  other  end  by  the  stop-cock.  By  this  expe- 
dient one  end  becomes  alternately  light  and  heavy,  and  thus 
produces  a  constant  oscillation  of  the  whole  trough  up  and 
down.  The  prints  to  be  washed  are  placed  in  these  troughs 
as  soon  as  they  leave  the  fixing  bath,  and  are  thus  kept  in 
motion  and  supplied  with  freshwater  for  any  length  of  time. 
Such  a  machine  is  called  the 

Self-Acting  Photographic  Washing '-Machine. 
When  prints  are  thus  treated  an  hour's  washing  will  re- 
move every  trace  of  the  hyposulphite  of  soda.  They  are 
then  taken  out  one  by  one  and  pinned  by  one  corner  to  slips 
of  wood,  or  suspended  on  varnished  hooks  inserted  into  corks, 
as  before  described  in  the  albumenizing  process. 

Mounting  of  Photographs. 
Photographs  may  be  cut  out  of  the  proper  size  and  shape 
either  before  they  are  starched  or  gummed  or  afterward. 
If  before,  the  following  is  the  mode  of  proceeding.  Place  a 
thick  plate  of  glass  before  you  on  the  table,  on  which  lay  the 
photograph,  picture  side  upward.  Next  place  over  this  a 
heavy  mat  in  such  a  position  as  to  present  the  best  appear- 
ance the  print  can  receive.  Holding  the  mat  firmly  in  its 
place,  by  means  of  the  first  and  second  finger  stretched  far 
apart,  with  a  sharp-pointed  penknife  cut  along  the  edge  of 
the  mat  through  the  paper  to  the  glass  all  the  distance  from 
the  end  of  the  second  finger  to  that  of  the  first.  If  you  stand 
to  perforin  this  operation  (a  position  to  be  preferred  to  that 
of  sitting)  move  gently  round  to  the  left,  still  holding  the 
fingers  firmly  on  the  mat.  Press  upon  the  mat  with  the 
right  hand,  whilst  the  second  finger  advances  to  the  position 
of  the  first,  and  this  one  is  again  stretched  asunder  to  a  new 
point  along  the  edge  of  the  mat.  Now  make  another  in- 
cision along  the  edge  in  perfect  continuity  with  the  first,  and 
thus  proceed  to  the  termination.  This  act  of  cutting  out  the 
prints  requires  considerable  dexterity  in  pressing  the  plate, 
and  making  the  incision  so  that  the  terminal  cut  is  a  conti- 
nuity of  the  commencement,  and  that  the  edge  all  round  is 


20G 


THE  FEINTING  OF  SENSITIZED  PAPEE. 


clean  and  not  dentatcd.  Where  the  business  is  extensive, 
it  is  advisable  to  fix  up  a  special  mounting  table  like  that 
used  by  potters  for  the  formation  of  utensils  out  of  the  plas- 
tic clay.  Such  a  table  can  be  turned  by  the  feet  on  a  verti- 
cal pedestal,  allowing  the  operator  to  sit  all  the  time.  A 
whetstone  or  hone  is  a  very  necessary  appendage  to  the 
mounting-table. 

The  prints  are  now  turned  over  and  brushed  over  with  a 
strong  solution  of  gum-arabic,  a  mixture  of  gum-arabic  and 
gelatine,  or  what  is  still  better,  with  a  solution  of  patent 
starch  or  dextrine,  such  as  is  used  on  the  back  of  post-stamps. 
Where  a  number  of  photographs  are  mounted  upon  the  same 
paper,  it  is  usual  to  brush  them  over  on  the  back  with  the 
solution  before  they  are  cut  out,  and  when  dry  to  perform 
the  operation  just  described.  The  starched  surface  is  then 
made  moist  by  going  over  it  with  a  moist  sponge.  The  print 
is  now  adjusted  upon  an  appropriate  mount  and  pressed  ac- 
curately clown  by  placing  first  a  sheet  of  clean  paper  over 
the  print,  so  that  its  edges  overlap  the  latter,  and  then  hold- 
ing the  first  and  second  finger  far  apart  and  firmly  on  its 
surface,  the  print  is  pressed  upon  the  cardboard  by  rubbing 
the  space  between  the  two  fingers  with  a  burnishing  tool  or 
with  the  smooth  handle  of  a  tooth-brush.  The  fingers  then 
assume  different  positions,  and  the  burnishing  is  continued 
until  the  whole  print  is  smoothly  and  evenly  adherent  to  the 
mounts  beneath. 

Photographs,  after  they  have  been  starched,  or  moistened 
after  starching,  can  be  mounted  much  more  quickly  by  first 
adjusting  them  to  their  place  on  the  mounts,  and  then  pass- 
ing them  beneath  the  rollers  of  a  glazing  or  planishing  ma- 
chine. The  two  operations  are  then  performed  at  one  and 
the  same  time.  This  planishing  is  quite  an  improvement  to 
a  print;  it  is  altogether  superior  to  varnishing  or  glazing. 
The  best  rolling  machines  are  those  furnished  with  a  hori- 
zontal bed,  like  that  in  a  lithographic  press.  Still  those  that 
consist  simply  of  a  pair  of  rollers  are  very  efficacious  in  pro- 
ducing decided  improvements  in  stereographs  or  card-pic- 
tures. 

Great  care  is  required  in  keeping  out  all  particles  of  sand 
from  the  starch  or  gum,  for  where  these  appear  they  produce 
protuberances  on  the  photographs  or  apertures  when  the 
prints  are  submitted  to  pressure  in  the  rolling-machines.  It 
is  therefore  always  necessary  to  remove  them  from  the  starched 
surface  before  it  is  placed  on  the  cardboard,  wherever  such 
particles  are  discovered  ;  and  to  obviate  the  repetition  of  such 


THE  PRINTING  OF  SENSITIZED  PAPER. 


207 


troubles  or  diminish  their  number,  it  becomes  the  duty  of  the 
operator  to  cover  his  gum  carefully  up  when  it  is  not  in  use. 

What  to  do  with  the  Clippings  of  Prints. 

Spoiled  prints,  soiled  sensitized  paper  and  the  cuttings  of 
pictures  may  as  well  be  preserved  as  not,  for  the  labor  con- 
sists simply  in  placing  them  in  some  corner  or  box,  instead 
of  throwing  them  away.  As  soon  as  the  stock  is  very  large, 
they  may  be  burnt  in  a  clean  stove  and  the  ashes  collected. 
These  ashes  contain  silver,  oxide  of  silver  and  other  combin- 
ations of  silver,  together  with  the  minerals  in  the  paper,  as, 
for  instance,  lime,  etc.  The  ashes  so  constituted  are  pressed 
closely  and  firmly  together  into  a  Hessian  crucible,  then  sub- 
mitted to  a  powerful  heat  and  thus  reduced.  Or  these  ashes 
may  be  mixed  with  the  chloride  of  silver,  obtained  by  preci- 
pitation of  old  baths  or  at  the  bottom  of  the  tanks  containing 
the  refuse  washing  water.  The  mass  is  first  well  dried,  then 
intimately  mixed  with  about  one  half  its  weight  of  either  car- 
bonate of  soda  or  potassa,  and  fused. 

In  large  establishments  the  refuse  silver  salts,  as  well  as 
the  cuttings  of  paper,  amount  to  quite  a  large  quantity  an- 
nually, and  are  sold  for  reduction  to  parties  who  make  it 
their  business.  Where  such  an  opportunity  presents  itself,  it 
is  more  advantageous  to  dispose  of  the  unreduced  refuse  than 
to  perform  the  operation  of  reduction  one's  self. 

Mounting  Stereographs. 
Stereoscopic  negatives  taken  from  nature  contain  two  pho- 
tographs, which,  when  printed,  are  inverted,  the  left  picture 
being  where  the  right  ought  to  be.  Some  photographers 
remedy  this  defect  by  cutting  the  negative  in  two  in  the 
middle,  and  then  proceeding  from  the  middle,  right  and  left, 
two  inches  and  three  quarters,  the  residual  slips  are  cut  qIF 
oil  the  ends  and  thrown  aside.  The  two  negatives  are  now 
placed  upon  a  thin  glass  stereoscopic  slide,  perfectly  clean, 
and  side  by  side  in  juxtaposition,  but  inverted,  so  that  the 
right-side  negative  is  placed  on  the  left  side.  By  means  of 
gummed  or  glued  ribbon  on  the  upper  edges,  these  negatives 
are  held  firmly  on  the  slide  beneath.  The  negatives  being 
so  arranged,  the  prints  will  have  the  right  position,  and  re- 
quire only  to  be  pared  at  the  top  and  bottom  previous  to 
mounting.  For  this  purpose  a  piece  of  glass,  with  rectangular 
corners  and  ground  edges,  five  inches  long  and  t  wo  inches  and 
a  half  wide,  is  placed  upon  the  prints  on  the  mounting-table 
or  slab  of  glass ;  with  a  sharp  penknife  go  round  th^  edges, 
taking  c#re  to  press  the  glass  form  firmly  on  the  prints.  In 


208 


THE  PRINTING  OF  SENSITIZED  PAPEE. 


this  way  the  pair  of  stereographs  will  be  cut  out  in  one  piece 
ready  for  gumming  and  mounting.  Copies  of  stereographs 
(if  taken  with  a  single  orthoscopic  lens)  do  not  require  the  ne- 
gative to  be  prepared  as  above  described ;  the  requisite  inver- 
sion exists  without  it. 

But  in  many  instances  the  negative  is  not  prepared  at  all 
in  tl lis  manner  fbr  printing,  but  left  in  its  natural  or  unaltered 
condition.  In  this  case  (and  it  is  probably  the  easiest  method 
of  proceeding)  the  glass  form  is  laid  upon  the  inverted  print, 
and  the  combined  prints  are  cut  out ;  after  which  another 
glass  form  of  exactly  half  the  size  is  laid  upon  one  end  of 
the  combined  prints,  which  are  then  cut  asunder.  The  larger 
glass  form  has  a  notch  on  the  top  and  bottom  edge  in  the  mid- 
dle ;  these  notches  are  placed  on  the  middle  line  of  the  print, 
and  serve  thus  to  direct  its  position.  If  this  middle  or  divid- 
ing line  between  the  two  prints  has  considerable  width,  which 
is  sometimes  the  case,  the  glass  form  must  be  in  proportion 
longer ;  but  the  smaller  form  retains  its  size  of  two  inches 
and  a  half.  Stereographs  of  groups  and  of  architectural  ob- 
jects are  frequently  cut  out  with  rounded  corners,  sometimes 
on  the  top  only,  and  sometimes  both  on  the  top  and  bottom. 
For  this  purpose  you  must  prepare  for  yourself  appropriate 
forms  of  glass,  by  grinding  down  the  corners  on  a  grind- 
stone, or  you  can  cut  out  the  requisite  shaped  mats  in  brass. 
Those  of  glass  are  by  far  the  easiest  to  construct. 

Mounts  for  stereographs  of  various  shades  of  color  can  be 
had  of  the  dealers  ;  these,  being  cut  by  machinery,  are  neater 
and  cheaper  than  those  you  can  make  yourself  from  cardboard. 
If  you  do  not  possess  the  power,  that  is,  have  not  cultivated 
the  faculty  of  seeing  stereoscopically  without  an  instrument, 
you  must  be  very  careful  not  to  invert  the  right  and  left  side 
pictures  between  the  cutting  and  mounting.  It  is  well  to  be 
provided  with  two  small  boxes,  one  marked  left  and  the  other 
right,  into  which  the  corresponding  prints  can  be  thrown  as 
soon  as  they  are  prepared  for  mounting.  The  mode  of  past- 
ing, adjusting  to  position,  and  passing  beneath  the  roller  is 
the  same  with  the  stereograph  as  that  with  the  ordinary  pho- 
tograph, which  has  been  already  described. 


* 


CHAPTER  XXXIII. 


bertrand's  new  process  for  positive  printing. 

Saxony  paper  is  the  best  for  this  process  ;  the  equality  of 
the  mass  is  not  absolutely  necessary,  but  that  which  contains 
iron  stains  must  be  rejected. 

The  first  preparation  of  the  paper  is  to  impregnate  it  with 
a  soluble  chloride ;  this  is  effected  by  plunging  it  into  the 
following  bath : 


The  paper  may  be  floated  on  the  surface  or  completely  im- 
mersed. The  most  expeditious  means  is  to  take  a  dozen 
sheets  and  immerse  them  one  by  one  in  the  bath,  by  means 
of  a  glass  triangle ;  when  a  certain  quantity  has  been  im- 
mersed, they  are  all  turned  over  at  once,  and  then  taken  out 
one  at  a  time  and  hung  up  to  dry ;  take  care  to  place  a  piece 
of  blotting-paper  in  contact  with  the  lowest  corner  of  each, 
in  order  to  produce  an  accumulation  of  fluid  in  this  place. 

The  sheets  dry  very  quickly ;  a  few  minutes  are  sufficient. 
If  necessary,  they  may  be  dried  by  artificial  heat. 

The  advantage  accruing  from  the  use  of  benzoin  is  to  fill 
up  completely  all  the  pores  of  the  paper ;  air  and  moisture 
can  no  longer  penetrate  into  the  interior  of  the  print,  which 
is  thus  protected  against  the  greatest,  if  not  the  only  cause 
of  deterioration.  Besides  this,  benzoin  communicates  to  pa- 
per the  gloss  of  albumen,  but  in  a  less  degree. 

The  chloridized  paper  will  keep  a  long  time ;  in  order  to 
sensitize  it,  place  it  in  contact  with  the  following  bath : 


exactly  as  for  albumen-paper. 

If  it  be  required  to  keep  the  sensitized  paper  for  some  time, 


Alcohol,  spec,  grav.,  .842, 

Benzoin,  

Chloride  of  cadmium,    .  . 


100  parts. 
10  " 
5  " 


Water,  .  .  .  . 
Nitrate  of  silver, 


100  parts. 
15  parts. 


210 


berteand's  new  peocess. 


it  may  be  placed  in  one  of  Marion's*  boxes,  where  it  will 
keep  perfectly. 

The  exposure  beneath  the  negative  is  much  shorter  than 
for  albumen-paper ;  the  picture  may  be  printed  deeper  than 
required  at  the  end  after  fixing.  If  the  time  has  been  too 
long,  the  blacks  become  deep  green,  but  there  is  no  necessity 
for  anxiety  about  the  matter,  the  toning  bath  will  restore 
them  to  their  original  black. 

The  prints  may  be  toned  either  in  the  Bayard  bath : 

Water,   1000  parts. 

Chloride  of  gold,   1  part. 

Chloride  of  ammonium,  .    .    .    .  20  parts. 

Hyposulphite  of  soda,   4  parts. 

or  in  the  acetate  bath  : 

Water,   .    .    .    1000  parts. 

Chloride  of  gold,   1  part. 

Acetate  of  soda,   30  parts. 

Glover's  JResinized  Printing  Process. 
Salting  Solution. 

Gum  thus,   180  grains. 

Gum  mastic,   40  grains. 

Chloride  of  zinc,   200  grains. 

Alcohol,   8  fluid  ounces. 

Sulphuric  ether,   2  ounces. 

The  object  of  adding  the  ether  is  to  insure  the  speedy  so- 
lution of  the  mastic.  The  paper  is  to  be  immersed  in  the 
above  for  five  minutes,  covering  the  dish  with  a  sheet  of 
glass  to  check  evaporation.  Take  out,  drain  closely,  and 
dry  before  the  fire.  Too  much  stress  can  not  be  laid  upon 
the  necessity  of  perfect  dryness,  so  that  if  the  salted  paper  be 
put  away  for  future  use,  it  must  again  be  held  some  time  be- 
fore the  fire,  previous  to  floating  on  the  silver  bath,  or  it  will 
not  take  up  the  solution  evenly.  The  silver  bath  is  composed 
as  follows  : 

Alcohol,  spec,  grav.,  .805,  ...     4  ounces.  1 

Gum  thus,   80  grains.  \-  Dissolve. 

Gum  mastic,  10  grains.  J 

Nitrate  of  silver,   960  grains.  >  Disgolye> 

Distilled  water,   4  ounces.  ) 

Mix  the  two  solutions  ;  shake  up  well ;  filter,  and  add  four 

*  This  box  is  oblong  or  square,  and  constructed  of  zinc,  with  a  tight-fit- 
ting cover.  At  the  bottom  there  is  a  plate  for  containing  fused  chloride  of 
calcium,  above  this  a  shelf  of  wire-gauze,  on  which  the  sensitized  sheets  are 
placed.  When  the  lid  is  accurately  closed,  whatever  moisture  may  be  in  the 
box,  it  will  be  absorbed  by  the  chloride,  which  is  a  very  deliquescent  salt. 


bertrand's  new  process. 


211 


drops  of  nitric  acid.  When  the  paper  has  been  in  contact 
with  the  above  solution  a  few  seconds,  it  has  a  tendency  to 
curl  up,  which  must  be  checked  by  breathing  upon  the  edges. 
After  it  has  settled  flat  on  the  surface,  allow  it  to  remain  ten 
seconds ;  it  is  then  ready  to  be  removed.  Take  hold  of  the 
sheet  by  one  corner,  and  stroke  it  with  a  glass  rod,  kept  for 
this  purpose  alone,  to  remove  the  surplus  solution,  and  dry  be- 
fore the  fire.  It  is  then  ready  for  fuming  over  a  dish  of  am- 
monia. This  last  operation  reduces  the  exposure  in  the 
printing  frame  about  one  third,  besides  insuring  success  in 
toning,  under  almost  every  condition  of  the  coloring  bath. 

On  removal  from  the  printing  frame,  wash  in  tepid  water, 
and  tone  by  any  of  the  alkaline  processes.  That  which  an- 
swers best  in  my  hands  is  composed  of  acetate  of  soda,  pre- 
pared at  least  twenty-four  hours  before  use,  with  the  addition 
of  a  few  drops  of  the  usual  solution  of  chloride  of  gold  im- 
mediately before  immersing  the  prints. 

Fix  in  a  nearly  saturated  solution  of  hyposulphite  of  soda, 
containing  five  per  cent  of  alcohol. 

The  subsequent  thorough  washing  must  not  be  neglected 
in  this  or  any  other  printing  process. 

Or  in  any  other  bath. 

The  print  soon  assumes  a  black  tone,  which  is  difficult  to 
obtain  with  albumen. 
It  is  finally  fixed  in 


As  soon  as  the  print  is  well  washed,  it  is  left  to  dry,  and 
afterward  brushed  over  with  a  piece  of  flannel,  or  a  pad  of 
cotton,  in  order  to  give  it  a  gloss.  It  is  evident  that  var- 
nishing is  useless. 


Water,  .  .  .  . 
Hyposulphite  of  soda, 


100  parts. 
20  parts. 


CHAPTER  XXXIV. 


PRINTING  BY  DEVELOPMENT. 

During  the  feeble  light  of  winter  in  high  northern  or 
southern  latitudes,  as  also  in  the  preparation  of  enlarged 
views  or  portraits  with  the  solar  camera,  printing  by  devel- 
opment is  of  very  great  utility.  It  is  quite  analogous  to  the 
operation  of  producing  a  collodion  picture  by  the  agency 
of  a  reducer ;  and  the  same  materials  in  general  are  em- 
ployed in  the  two  branches. 

Formula  for  the  Salting  Solution. 
No.  1.    With  the  Chlorides. 
Chloride  of  sodium,  (common  salt,)    .    .    .  100  grains. 

Hydrochloric  acid,   6  drops. 

Rain-water,  12  ounces. 

Immerse  the  papers  in  this  mixture  and  let  them  remain  in 
it  for  two  or  three  hours,  then  take  them  out  and  allow  them 
to  dry. 

Formula  for  Sensitizing  Solution. 

Nitrate  of  silver,  1  ounce. 

Citric  acid,  8  grains. 

Distilled  or  rain-water,  8  ounces. 

Float  the  papers  on  this  solution  for  three  minutes,  and  then 
suspend  them  on  the  varnished  needles,  or  on  a  cord  with 
clothes-pins.  Remove  all  the  fluid  that  accumulates  on  the 
lower  side  or  on  the  corners.  As  soon  as  the  papers  are 
moderately  dry  they  may  be  exposed  beneath  the  negative 
or  on  the  screen  of  the  solar  camera  until  &  faint  image  ap- 
pears. Beneath  a  negative  in  the  rays  of  the  sun,  the  time 
of  exposure  will  not  exceed  three  or  four  seconds ;  in  feeble 
light  a  minute  or  more  may  be  required.  As  soon  as  the 
print  is  sufficiently  distinct,  it  is  withdrawn  and  laid  upon  a 
piece  of  glass  somewhat  smaller  in  dimensions  than  the  pa- 
per, picture  side  upward  ;  two  opposite  edges  of  the  paper 
are  folded  beneath  the  glass,  and  in  this  position  the  paper 
and  the  glass  together  are  placed  on  the  left  side  of  a  capa- 
cious gutta-percha  developing  dish. 


PRINTING  BY  DEVELOPMENT. 


213 


Formula  for  Developing  Solution. 

Pyrogallic  acid,    .    .    .    .  12  grains. 

Citric  acid.,  6  grains. 

Water,  6  ounces. 

Of  this  solution  take  sufficient  to  cover  the  paper.  Inclining 
the  dish  downward  to  the  right  side,  pour  in  the  solution  ; 
then  dexterously  raising  the  right  side,  the  fluid  will  flow  or 
may  be  made  to  flow  over  the  whole  surface  without  pro- 
ducing any  lines  of  stoppage.  This  is  very  important,  be- 
cause any  stoppage  on  such  paper  would  be  as  injurious  as 
on  collodion  prints.  The  development  commences  and  pro- 
ceeds as  rapidly  as  on  a  collodion  negative,  and  requires  just 
the  same  amount  of  vigilance.  As  soon  as  the  proper  con- 
trast has  been  attained,  the  further  reduction  is  caused  to 
cease  by  pouring  off  the  developer  into  the  sink  or  waste- 
tub,  and  then  by  washing  at  the  tap.  The  Avashing  must  be 
performed  with  care  and  effectually.  After  this  operation 
the  prints  are  fixed  in  the  folloAving  solution  : 

Formula  for  the  Fixing  Solution, 

Hyposulphite  of  soda,  1  ounce. 

Water,  16  ounces. 

The  prints  are  kept  in  this  solution  until  the  whites  are  per- 
fectly clear,  which  will  require  from  ten  minutes  to  half  an 
hour.  They  are  then  taken  out  and  submitted  to  the  regu- 
lar process  of  washing,  in  order  to  remove  every  trace  of 
the  hyposulphites. 

Second  Method  ivith  a  Chloride  and  a  Bromide, 
Formula  for  Salting  the  Paper. 


White  of  egg,  10  ounces. 

Distilled  water,  15  ounces. 

Chloride  of  sodium,  .    .  *   1  drachm. 

Bromide  of  potassium,  1  drachm. 


Dissolve  the  salts  in  the  water  and  add  the  solution  to  the 
albumen,  which  has  to  be  beaten  up  into  a  froth  and  allowed 
to  subside  several  hours  in  a  cool  place.  The  clear  super- 
natant liquid  is  decanted  carefully  or  filtered  from  the  de- 
posit into  the  appropriate  dish  for  salting  operations. 

The  papers  are  floated  in  the  ordinary  way  on  the  surface 
of  this  bath  for  three  minutes,  and  then  hung  up  to  dry  on 
cords  and  attached  by  means  of  clean  clothes-pins.  After 
this  operation  the  papers  are  put  in  a  long  tin  box  which  is 
inserted  in  a  deep  kettle  of  boiling  water,  taking  care  that 
none  of  the  water  can  get  access  to  the  paper,  but  that  the 


214 


PRINTING  BY  DEVELOPMENT. 


paper  is  submitted  through  its  whole  length  to  the  heat  of 
steam  ;  the  operation  is  still  more  effectual  if  hot  steam  could 
come  in  contact  with  the  albumenized  surface  ;  such  an  ex- 
pedient is  intended  to  coagulate  the  albumen.  The  omission 
of  this  part  of  the  operation  must  not  deter  the  operator 
from  trying  the  process  ;  the  results  will  not  materially  be 
changed,  because  the  coagulation  can  be  effected  in  the  sen- 
sitizing bath. 

Formula  for  the  Sensitizing  Solution. 

Nitrate  of  silver,  1  ounce. 

Distilled  water,  12  ounces. 

Citric  acid,  3  drachms. 

Alcohol,  1  ounce. 

The  papers  are  floated  on  this  bath  from  two  to  three  min- 
utes, and  are  then  allowed  to  dry  as  usual.  An  exposure  of 
from  eight  to  ten  seconds  in  the  full  sun  will  be  sufficient ; 
whilst  as  many  minutes  will  be  required  in  a  weak  light. 
The  picture  must  be  quite  visible,  or  very  nearly  so,  before 
it  can  be  said  that  the  exposure  is  long  enough. 

Developing  Solution. 

Gallic  acid,  5  grains. 

Distilled  water,  2  ounces. 

The  operation  of  development  is  best  performed  in  a  glass 
or  gutta-percha  dish  ;  the  print  is  first  moistened  and  then 
placed  on  the  bottom  of  the  vessel  to  which  it  adheres.  The 
developing  fluid,  being  poured  on  the  inclined  right-hand 
side,  is  flowed  over  the  print  almost  instantaneously  ;  if  any 
part  remains  not  covered,  a  slight,  quick  motion  will  easily 
bring  the  fluid  over  the  part,  or  a  glass  triangle  will  cause 
the  difficulty  to  disappear,  dragging  along  with  it  sufficient 
of  the  fluid  to  cover  the  part  denuded.  The  reduction  is 
very  rapid  ;  and  where  the  exposure  has  been  about  right, 
the  development  of  the  image  will  be  complete  in  two  or  three 
minutes.  In  very  cold  weather  it  is  better  either  to  use  a 
stronger  bath  or  to  warm  the  bath  by  floating  it  in  warm 
water.  Gallic  acid  in  solution  is  very  apt  to  become  mouldy 
by  keeping,  and,  consequently,  a  small  piece  of  camphor,  or 
a  drop  of  oil  of  cloves,  is  mixed  with  the  bath  to  prevent  this 
sort  of  decomposition.  An  under-exposed  picture  develops 
very  slowly,  and  by  a  long  continuance  of  the  action  of  the 
acid  it  becomes  uniformly  dark-colored  without  any  grada- 
tion of  tone  ;  on  the  contrary,  an  over-exposed  picture  is 
developed  with  great  rapidity,  and  has  to  be  removed  from 
the  bath  quickly  to  prevent  its  assuming  a  dark  color  over 


PRINTING  BY  DEVELOPMENT. 


215 


the  whites.  If  printed  deep  enough  in  the  shades,  in  such  a 
case,  the  lights  would  in  the  mean  while  be  completely 
spoiled.  The  best  prints  are  those  in  which  the  gradation 
is  all  thoroughly  and  rather  slowly  brought  out  in  the  print- 
ing ;  these  are  afterward  carefully  washed  and  fixed  in  a 
weak  solution  of  hyposulphite  of  soda,  containing  as  follows : 

Hyposulphite  of  soda,  1  ounce. 

Water,  20  ounces. 

The  prints  remain  in  this  solution  for  a  quarter  of  an  hour 
or  so,  and  are  again  thoroughly  washed.  After  this  proceed 
ing,  if  the  tones  are  not  satisfactory,  the  prints  may  be  im- 
mersed in  the  gold  toning-bath,  in  order  to  receive  a  gold 
deposit,  which  modifies  the  color.  Any  of  the  gold-toning 
formulas  given  will  answer  the  purpose.  If,  in  the  opera- 
tion of  developing,  etc.,  the  whites  are  not  clear,  an  improve- 
ment in  this  respect  is  effected  by  immersing  the  well- washed 
prints  in  a  bath  containing  one  ounce  of  chlorinetted  lime  to 
ten  ounces  of  water. 

Third  Method  with  an  Iodide. 
Formula  for  Salting  Solution. 


{  Nitrate  of  silver,  44  grains. 

"  (  Distilled  water,  2  ounces. 

,  (  Iodide  of  potassium,  7  drachms. 

'■  |  Distilled  water,  2  ounces. 


Dissolve  the  two  salts,  and  then  mix  the  solutions  together, 
which  will  produce  a  precipitate  of  the  yellow  iodide  of 
silver.  Add  to  this  a  concentrated  solution  of  iodide  of 
potassium,  until  the  precipitate  is  dissolved.  The  fluid  is 
then  ready  for  the  bath. 

Float  the  papers  on  this  bath  in  the  usual  manner  for 
about  three  minutes,  or  until  they  lie  flat  on  the  solution. 
They  are  then  taken  out  and  hung  up  to  dry.  After  this 
proceeding  they  are  floated  in  a  quantity  of  rain-water,  two 
and  two  together  and  back  to  back,  for  a  number  of  hours, 
taking  care  to  turn  them  over  from  time  to  time.  The  sur- 
face thus  prepared  assumes  a  very  uniform  but  pale  yellow 
color.    The  papers  are  again  taken  out  and  hung  up  to  dry. 

Sensitizing  Bath.  Formula. 

Distilled  water,  25  ounces. 

Aceto-nitrate  of  silver  solution,    ....     4  drachms. 

The  solution  of  aceto-nitrate  of  silver  is  prepared  as  fol- 
lows : 


216 


PRINTING  BY  DEVELOPMENT. 


Nitrate  of  silver, 
Ace  tie  acid,  . 
Distilled  water, 


1  ounce. 

2  ounces. 
10  ounces. 


Or  the  complete  formula  may  stand  as  follows,  where  oper- 
ators do  not  wish  to  keep  a  stock  of  the  aceto-nitrate  of 
silver  : 


The  papers  are  floated  on  this  bath  for  three  minutes,  and 
then  taken  out  and  hung  up  to  dry.  Whilst  the  surface  is 
still  somewhat  moist,  they  are  exposed  beneath  a  varnished 
^negative,  or  on  the  screen  of  the  solar  camera,  for  a  few 
seconds.  The  image  in  this  case  is  quite  latent.  In  dull 
wTeather,  and  when  the  light  is  very  feeble,  half  a  minute's  ex- 
posure will  suffice.  The  print  is  developed  by  pouring  upon 
it,  in  the  manner  already  indicated,  a  saturated  solution  of 
gallic  acid  containing  about  one  third  its  quantity  of  aceto- 
nitrate  of  silver.  If  the  development  is  very  slow,  the  ex- 
posure has  been  too  short ;  on  the  contrary,  the  develop- 
ment is  quite  rapid  when  the  exposure  has  been  too  long. 
As  soon  as  the  print  is  completely  brought  out  in  all  its  de- 
tails, it  is  immersed  in  water  and  very  thoroughly  washed 
in  order  to  remove  every  trace  of  gallic  acid. 

The  prints  are  then  immersed  in  a  solution  of  hyposulphite 
of  soda  as  follows  : 

Hyposulphite  of  soda,  2  ounces. 


The  prints  do  not  change  much  by  immersion  in  the  fix- 
ing solution,  if  the  time  of  exposure  has  been  sufficiently  pro- 
longed; if  the  time  has  been  too  short,  the  dark  color  will  be- 
come pale  and  red.  If  the  tones  of  the  shades  do  not  assume 
a  dark  color  in  the  developing  solution,  the  cause  may  be 
attributed  to  the  want  of  aceto-nitrate  of  silver  in  the  gallic 
acid;  and,  as  a  rule  to  be  observed,  the  aceto-nitrate  is 
gradually  added  where  the  development  or  the  intensity 
relax.  If  the  toning  in  the  fixing  solution  becomes  inky,  the 
gold  may  be  omitted. 

Method  of  Sensitizing  by  Means  of  N~itrate  of  Uranium. 
{The  Process  of  Niepce  de  Saint  Victor) 
The  paper  used  in  this  operation  has  to  be  kept  in  the 
dark-room,  or  at  least  excluded  from  light,  for  several  days 
previous  to  its  employment.  It  is  then  floated,  without  any 
other  preparation,  on  the  following  bath  : 


Distilled  water, 
Nitrate  of  silver, 
Acetic  acid,   .  , 


25  ounces. 
18  grains. 
2  scruples. 


Water,  .  .  . 
Chloride  of  gold, 


10  ounces. 
2  grains. 


PRINTING  BY  DEVELOPMENT. 


217 


Sensitizing  Bath. 

Nitrate  of  uranium,  1  ounce. 

Distilled  water,  5  ounces. 

After  two  or  three  minutes  the  papers  are  removed  from 
the  bath,  allowed  to  drain,  and  then  hung  up  and  dried. 
They  will  keep  a  long  time  when  not  exposed  to  light.  The 
time  of  exposure  beneath  a  negative  varies  with  the  intensi- 
ty of  the  light ;  from  one  to  ten  minutes  in  the  sun,  and  from 
a  quarter  of  an  hour  to  an  hour  in  a  feeble  diffused  light. 
The  image  is  barely  visible. 

Developing  Solution.    No.  1. 

Nitrate  of  silver,  1  drachm. 

Acetic  acid,  1  to  2  drops. 

Distilled  water,  2  ounces.  :  / 

The  development  is  very  rapid.  Almost  as  soon  as  the 
print  is  immersed  in  the  fluid,  the  picture  comes  out  and 
proceeds  to  its  termination  with  great  velocity.  As  soon  as 
the  development  has  advanced  far  enough,  the  prints  are 
plunged  into  water,  and  thus  washed  and  fixed  at  the  same 
time. 

Developing  Solution.    No.  2. 

Chloride  of  gold,  10  grains. 

Hydrochloric  acid,  1  drop. 

Distilled  water,  12  ounces. 

Prints  are  developed  in  this  bath  with  more  rapidity  than 
in  the  preceding. 

Another  Method. 
Sensitising  Bath. 

Nitrate  of  uranium,  1  ounce. 

Distilled  water,   10  ounces. 

Developing  Solution. 

Bichloride  of  mercury,  5  grains. 

Distilled  water,  12  ounces. 

Pass  the  prints  through  this  solution,  and  then  wash  them 
very  carefully,  after  which  they  are  immersed  in  the  follow- 
ing bath : 

Nitrate  of  silver,  2  drachms. 

Distilled  water,  12  ounces. 

When  the  image  is  intense  enough,  wash  the  prints  thor* 
oughly  and  hang  them  up  to  dry. 
10 


CHAPTER  XXXV. 


THE  CAED-PICTURE. 

This  picture  does  not  differ  from  any  other  photograph  in 
the  essential  parts  of  its  structure  or  preparation.  ]STo  pic- 
ture has  ever  had  so  wide  a  sphere  o£-action,  has  gratified 
taste  so  long,  or  has  been  as  productive  of  gain  to  the  pho- 
tographer as  the  card-picture.  It  is  the  picture  of  the  day, 
and  has  tended  considerably  to  simplify  the  photographic  es- 
tablishment. A  few  years  past  a  number  of  cameras  were 
required,  ranging  from  the  quarter  to  the  extra  four  fourth 
tube  ;  now,  a  single  tube,  either  a  one  fourth  or  a  one  third 
will  be  a  complete  outfit  as  regards  lenses  for  an  ordinary 
practitioner,  with  which,  Deo  volente,  and  the  war  to  boot,  a 
fortune  may  soon  be  realized.  The  card-picture  generally 
comprehends  the  whole  figure,  either  sitting,  standing,  grace- 
fully leaning  against  a  pillar  or  balustrade,  performing  some 
natural  and  easy  operation,  as  playing  the  piano  or  guitar, 
trimming  a  flower  in  the  arbor,  or  sailing  in  the  yacht ;  in  fact, 
the  photographer,  at  least  the  artist,  aims  to  pose  his  model 
in  the  midst  of  nature's  charms  with  ease  and  grace,  and  per- 
fectly free  from  all  constraint. 

The  size  of  the  card-picture  is  a  distinct  characteristic  from 
all  other  pictures.  The  mounts  of  cardboard  for  this  picture 
are  four  inches  long  by  two  inches  and  one  third  wide  ;  they 
can  be  had  already  prepared,  plain  or  ornamented,  with  gilt 
edges,  or  with  a  gilt  border,  at  any  of  the  photographic 
wholesale  establishments  in  the  city.  The  prints  are  smaller 
than  the  mounts,  leaving  a  margin  of  about  one  tenth  of  an 
inch  on  either  side  and  on  the  top  ;  the  margin  at  the  bottom 
is  larger,  being  about  a  quarter  of  an  inch.  The  paper  on 
which  such  pictures  are  printed  is  of  the  finest  quality,  and 
very  uniformly  and  highly  albumenized.  It  is  impossible  to 
obtain  the  fine,  sharp  definition  on  plain  paper  as  on  albu- 
men, because  of  the  difference  of  homogeneity  in  the  two 
surfaces.  Tinted  albumen  paper,  too,  is  now  sometimes  used 
to  meet  the  wishes  of  the  fanciful,  or  the  cravings  after  novelty. 


THE  CARD-PICTURE. 


219 


Lenses  for  the  Card-Picture. 
Lenses  for  the  card-picture  are  prepared  with  great  care, 
so  as  to  produce  as  little  distortion  as  possible  in  the  com- 
plete figure.  On  this  account  a  long-focussed  tube  is  prefer- 
red to  one  that  is  shorter  ;  but  of  two  tubes,  if  they  both  pro- 
duce irreproachable  pictures  in  a  given  room,  the  one,  which 
is  the  result  of  the  short-focussed  instrument,  will  exhibit 
more  roundness,  a  finer  stereoscopic  effect  than  the  other. 
Choose  therefore  the  shortest  tube  that  will  perform  all  that 
is  required  in  a  card-picture,  and  at  the  distance  which  your 
glass-house  will  admit  of.  Where  the  business  in  this  depart- 
ment is  extensive,  two  tubes,  or  even  four  tubes  afe  mounted  at 
the  requisite  distance  apart  for  the  taking  of  two  or  four  photo- 
graphs at  the  same  time.  Furthermore,  by  an  arrangement 
of  the  plate-holder  in  the  camera,  by  which  it  is  caused  to 
slide  either  horizontally  or  vertically,  or  in  both  directions, 
as  many  as  eight  or  sixteen  photographs  can  be  taken  at  the 
same  sitting.  It  would  be  a  waste  of  time  to  get  up  such 
cameras  one's  self ;  they  are  manufactured  very  neatly  and 
accurately  by  city  artisans,  and  are  fitted  up  with  the  num- 
ber of  tubes  ordered  or  required.  Each  tube  is  focussed  se- 
parately upon  the  sitter,  and  then  by  a  shutter  the  tubes  are 
opened  and  shut  cosentaneously  at  will.  After  a  proper 
number  of  seconds  have  expired,  the  shutter  is  closed,  and 
the  plate-holder  is  moved  a  fixed  distance,  so  as  to  expose 
another  portion  of  the  collodion  plate.  In  the  mean  while  the 
model  remains  quite  still.  The  shutter  is  again  opened  and 
the  plate  exposed  as  before. 

Development. 

This  operation  scarcely  needs  any  elucidation ;  the  proper 
negative  effect  has  to  be  attained  by  means  of  the  reducing 
agent  and  the  intensifier  as  before  minutely  described.  The 
image  is  by  far  softer,  and  in  other  respects  more  agreeable, 
if  the  negative  can  receive  its  requisite  amount  of  density  by 
the  primary  development,  or  nearly  so,  so  that,  when  inten- 
sified, but  little  more  has  to  be  accomplished,  and  this  little 
can  be  effected  by  a  weak  intensifier.  When  the  strengthen- 
ing solution  is  very  strong,  it  is  apt  to  engender  a  pulveru- 
lent deposit  on  the  surface  of  the  collodion  which  detracts 
from  softness  and  sharpness,  communicating  to  the  photo- 
graph an  appearance  of  measles  or  small-pox.  In  this  re- 
spect it  is  indifferent  whatever  may  be  the  size  of  the  nega- 
tive, where  there  is  a  tendency  to  this  powdery  phenomenon, 
whether  it  arise  from  the  collodion,  or,  as  I  have  just  re- 


220 


THE  CARD-PICTURE. 


marked,  from  a  deposit  of  the  silver,  it  is  always  advisable 
to  intensify  slowly. 

One  point  in  the  taking  of  negatives  I  have  not  yet  ad- 
verted to.  In  the  wet  process,  if  the  sensitized  plate  has  to 
wait  long  between  the  time  of  its  removal  from  the  silver 
bath  and  its  development,  the  silver  solutidn  evaporates  ra- 
pidly, and  the  plate  becomes  dry,  or  nearly  so ;  the  conse- 
quence of  this  is  supposed  to  be,  that,  as  the  solution  thus  be- 
comes stronger,  it  dissolves  the  iodide  of  silver  in  the  film, 
and  gives  rise  to  the  phenomenon  of  minute  apertures.  With- 
out attaching  much  credit  to  this  rationale  of  a  trouble  wThich 
is  very  annoying,  we  do  know  that  if  the  silvered  plate  be- 
comes dry  the  development  is  very  irregular.  Another  cause 
of  the  minute  apertures  alluded  to  is  a  quantity  of  insoluble 
bromide  in  the  collodion.  It  is  a  recommendation,  therefore, 
to  dissolve  the  iodides  and  bromides  in  the  preparation  of 
collodion,  first  in  alcohol,  and  to  filter  the  solution,  after 
standing  several  hours,  before  it  is  added  to  the  plain  collo- 
dion. Another  reason,  and  probably  a  very  frequent  one,  is 
to  be  traced  to  the  minute  insoluble  particles  in  the  silver 
bath,  which  settle  upon  the  tender  collodion  film,  and  become 
as  it  were  imbedded  in  it.  These  in  the  subsequent  opera- 
tions of  developing  and  fixing  produce  either  opaque  pulver- 
ulent black  points,  or  transparent  ones,  just  as  they  retain  a 
fixed  position  in  or  on  the  film,  or  are  wrashed  or  dissolved  off. 
Both  these  phenomena  are  exceedingly  annoying.  Such  a 
cause  can  be  removed  by  filtration,  or  by  a  sort  of  coagula- 
tion, (if  I  may  use  the  word  here  instead  of  precipitation,) 
by  means  of  a  small  quantity  of  a  solution  of  salt,  and  then 
by  filtration.  This  operation  certainly  weakens  the  bath, 
but  it  makes  it  at  the  same  time  a  better  solvent  of  certain  im- 
purities that  tend  to  cause  the  trouble  in  question.  The  ten- 
dency to  these  horrid  pin-holes  is  greater  when  the  bath  is  strong 
than  when  it  is  weak  ;  it  would  appear,  however,  that  the  in- 
soluble iodide  of  silver  in  the  film  can  scarcely  be  a  cause  of 
the  trouble;  for  being  present  everywhere  in  the  film,  it 
would  be  uniformly  dissolved  as  the  silver  solution  gradually 
increased  in  strength,  and  would  thus  present  a  condition  for 
actinism  the  very  best  that  could  be  desired.  There  is  cer- 
tainly no  doubt  that  these  apertures  are  caused  in  the  ma- 
jority of  cases  by  an  insoluble  pulverulent  substance,  loosely 
attached  to  the  surface  of  the  collodion,  and  either  sensitive 
to  the  actinic  rays  or  not,  (which  is  quite  immaterial  to  the 
argument ;)  these,  imbedded  on  the  surface  of  the  collodion 
and  opaque,  prevent  the  rays  from  penetrating  to  the  true 


THE  CARD-PICTTTKE. 


221 


film  beneath,  and  being  afterward  brushed  off  or  dissolved 
off  by  the  acids  in  the  developer  or  by  the  fixing  solution, 
expose  parts  in  which  the  iodides  and  bromides  have  not  un- 
dergone the  luminous  influence,  and  are  hence  made  trans- 
parent by  the  hyposulphite  of  soda,  like  any  other  protected 
part. 

In  fine,  no  general  rule  is  known  by  which  a  priori  these 
pin-holes  can  always  be  avoided  and  accounted  for. 

The  card-negative,  next  to  that  which  is  prepared  for  the 
solar  camera,  must  be  bright  and  transparent,  free  from  the 
slightest  trace  of  mistiness  or  fogging,  and  of  such  a  depth 
of  shade  as  to  preserve  the  whites,  whilst  at  the  same  time 
the  operation  of  printing  is  performed  quickly.  That  the 
negative  must  be  sharp  is  a  sine  qua  non  y  and  in  order  that 
the  negative  be  sharp  and  well-defined  to  the  very  edge, 
and  from  top  to  toe,  spare  no  expense,  no  trouble  in  securing 
a  reliable  lens.  With  this,  and  a  moderate  share  of  intelli- 
gence, an  operator  may  run  his  career  without  impediment 
to  success ;  whilst  his  neghbors,  with  poor  lenses,  whatever 
their  amount  of  education,  will  roll  down  the  hill  to  perdition. 
The  tens  leads  to  success  or  to  ruin. 

Fixing. 

There  is  no  difference  in  this  department  from  that  which 
will  be  found  in  reference  to  the  melainotype,  or  the  ordi- 
nary negative.  Either  cyanide  of  potassium  or  hyposulphite 
of  soda  is  used.  The  new  fixing  agent,  sulphocyanide  of 
ammonium,  it  appears  has  no  claims  of  superiority  over  its 
predecessors ;  it  has,  however,  a  decided  disadvantage,  and 
that  is  its  expense ;  this  will  always  exist  comparatively, 
because  cyanide  of  potassium  can  more  easily  be  manufac- 
tured. Like  the  cyanide,  too,  it  has  toxical  properties.  In 
order  to  avoid  all  the  poisonous  effects  that  might  arise  from 
contact  of  such  substances  with  the  broken  skin  or  wounds, 
as  well  as  the  discoloration  of  the  skin  from  the  silver  salts 
during  development,  I  would  recommend  a  plan  which  I 
generally  adopt.  I  do  not  hold  the  negative  in  the  hand 
when  I  intensify ;  it  is  placed  on  a  piece  of  glass  cut  out 
in  the  form  of  the  porcelain  dipper  for  the  silver  bath.  At 
one  end  a  small  piece  of  thick  glass,  one  inch  in  width,  and 
as  long  as  the  cftpper  is  wide,  is  cemented  by  melted  lac ; 
over  this  is  cemented  a  second  piece,  projecting  above  the 
first  one,  so  as  to  form  a  ledge  beneath  which  the  nega- 
tive is  kept  in  its  place.  At  the  upper  end  the  negative  is 
secured  in  its  place  by  means  of  a  clothes-pin.  In  this  way  the 


222 


THE  CARD-PICTURE. 


negative  can  be  intensified  without  obscuring  the  light  that 
passes  through  it  from  below7*,  and  the  hand  at  the  same  time 
is  protected  from  contact  with  the  pyrogallic  acid  and  silver. 
Stains  from  nitrate  of  silver,  or  from  the  pyrogallate  can  be 
removed,  it  is  true,  as  long  as  they  have  not  been  exposed 
much  to  light,  by  washing  with  cyanide  of  potassium ;  but 
this  would  entail  upon  the  operator  the  trouble  of  washing 
after  each  negative,  and  might  entail  upon  him  incurable  ul- 
cers. If  he  does  not  wash  his  hands  after  each  negative  has 
been  taken,  there  is  no  alternative,  they  must  inevitably  be- 
come black.  The  glass  dipper  will  obviate  this  trouble.  An- 
other trouble,  but  not  quite  so  alarming,  arises  from  the  mode 
we  practise  of  turning  the  prints  round  with  the  hands  in  the 
toning  and  fixing  baths.  The  health  of  operators  is  much 
impaired,  and  especially  in  those  large  printing  establish- 
ments, where  a  number  of  females  are  employed  in  this  de- 
partment, who,  by  this  continual  manipulation  in  the  two 
fluids,  are  frequently  in  a  suffering  condition  Now  all  this 
can  be  avoided  by  a  dexterous  use  of  a  glass  rod,  well  rounded 
off  at  either  end,  and  held  in  either  hand.  The  hands  have 
no  business  in  these  fluids  /  and  all  parties  concerned,  that  is, 
hands,  fluids,  and  prints,  will  be  benefited  by  following  the 
precaution  recommended.  With  a  little  ingenuity  a  pair  of 
porcelain  or  glass  forceps  might  be  constructed  for  this  spe- 
cial purpose,  consisting  of  porcelain  or  glass  legs  fastened 
into  a  steel  spring  arch,  which  would  hold  them  an  inch  or 
so  asunder.  Such  forceps  may  be  used,  too,  in  holding  the 
negative  either  during  development  or  intensifying.  The 
health  of  the  photographer  has  to  be  looked  to,  and  means 
adopted  for  its  preservation. 

Printing  of  Card -Pictures, 
There  is  nothing  peculiar  in  the  printing  of  card-pictures, 
photographically  speaking,  as  distinct  from  that  in  other  pic- 
tures on  paper,  except  it  be  the  number  of  photographs  on 
the  same  plate ;  for,  as  was  to  be  inferred  from  the  manner 
prescribed  to  take  the  negative,  this  plate  may  contain  as 
many  as  sixteen  distinct  pictures ;  it  seldom,  however,  con- 
tains as  many.  Condensing  reflectors  find  their  application 
here  to  great  advantage  when  the  light  is  dull.  Such  an  ar- 
rangement of  reflectors  might  be  constructed  on  a  movable 
platform,  or  turn-table,  capable  of  rotating  horizontally, 
whilst  the  frustum  itself,  lined  by  the  reflectors,  and  sup- 
ported on  vertical  pillars,  has  a  vertical  motion.  By  the 
two  motions  combined,  the  frustrum  can  be  easily  brought 


THE  CAED-PICTUKE. 


223 


in  front  of  the  direct  rays  of  the  sun,  whereby  a  great  con- 
densation of  light  can  be  effected  on  any  given  surface.  It 
is  immaterial  how  large  a  surface  may  be  occupied  by  the 
negative,  or  the  sum  of  the  negatives  on  the  same  plate, 
reflectors  can  be  made  in  accordance,  possessing  the  advan- 
tage of  the  direct  rays  that  strike  the  plate,  as  in  ordinary 
printing,  together  with  the  extra  advantage  of  the  condensed 
light  from  the  rays  after  one  reflection,  as  well  as  from  those 
after  two  reflections.  The  size  of  each  of  the  reflectors  al- 
luded to  will  be  proportionate  to  that  given  in  a  preceding 
chapter.  If  the  negative  plate  be  sixteen  inches  square,  then  it 
will  be  four  times  as  large  in  its  linear  dimensions,  as  in  the  ex- 
ample given  ;  consequently,  multiplying  14r7o87  and  21^%-  by 
this  ratio,  that  is  4,  we  obtain  59T' ^\  and  85^0  inches  for  the 
length  of  the  upper  or  larger  base,  and  86f%4o  inches  for  the 
length  of  the  side  of  each  plate  of  glass  in  the  frustum.  Such 
a  machine,  of  course,  will  be  expensive,  but  like  a  wind-mill 
where  no  water  exists,  it  will  soon  pay  for  its  construction 
by  economizing  time.  By  such  a  condensation  of  the  sun's 
rays,  a  negative  will  print  well  in  from  thirty  to  sixty  seconds. 

Vignette  Printing. 

A  vignette  is  a  picture  of  a  portrait,  consisting  of  the  head 
and  part  of  the  bust,  of  an  oval  shape,  in  the  middle  of  the 
card,  surrounded  by  a  sort  of  halo,  or  shading  off  gradually 
into  the  white  background. 

For  this  sort  of  printing  the  operator  has  to  be  furnished 
with  vignette  glasses,  which  are  manufactured  specially  for 
such  operations,  and  to  be  had  of  all  respectable  dealers. 
The  vignette  aperture  can  be  had  of  any  size  required ;  it  is 
formed  of  a  piece  of  glass,  stained  on  one  or  on  either  side 
with  a  metallic  oxide,  which  is  burnt  into  the  glass.  This 
stain,  however,  is  a  mere  film,  and  can  easily  be  ground  away 
of  the  requisite  shape  and  size  by  the  lapidary,  and  then  pol- 
ished. The  external  parts  being  of  a  red  orange  color,  in- 
tercept or  absorb  those  rays  of  light  which  would  act  upon 
the  sensitized  collodion  film,  whilst  through  the  vignette 
opening  all  the  rays  can  act  almost  with  their  primitive 
vigor.  Such  a  glass,  or  an  appendage  of  such  glasses,  is 
placed  first  on  the  glass  of  the  printing-frame ;  upon  this 
comes  the  negative,  and  then  the  paper,  as  in  ordinary  print- 
ing arrangements. 

Vignette  glasses  can  be  made  by  the  photographer  himself 
in  the  following  manner  :  Take  a  piece  of  glass  of  the  proper 
size,  and  paint  either  with  water  or  oil  colors  the  vignette 


224 


THE  CARD-PICTURE. 


opening  in  orange  or  black,  shading  off  toward  the  edges ; 
till  up  the  remaining  part  with  white  paint,  shading  the  edges 
bordering  on  the  vignette  gradually  deeper  and  deeper,  until 
the  layer  becomes  uniformly  white  to  the  edges  of  the  glass. 
This  is  the  matrix  from  which  an  indefinite  number  of  nega- 
tives can  be  copied,  which  will  be,  when  varnished,  the  vig- 
nettes required. 

Toning,  Fixing,  and  Mounting. 
No  further  observations  are  requisite.  Instructions  on 
these  matters  are  given  in  detail  in  a  preceding  chapter  of 
this  work,  and  on  the  coloring  of  the  card-picture,  of  the  ste- 
reograph and  the  photograph  in  a  chapter  specially  devoted 
to  the  subject. 

On  the  Tinting  and  Coloring  of  Photographs. 

The  colors  required  to  tint  or  color  photographs  are  the 
same  as  those  employed  in  miniature  painting,  and  the  same 
amount  of  artistic  skill  is  required  in  the  one  as  in  the  other, 
where  excellence  and  perfection  are  the  aim  of  the  photo- 
grapher. Where  very  large  photographs  are  to  be  colored, 
the  fineness  of  miniature  painting  for  hatching  or  stippling 
is  not  essential,  in  fact  it  would  be  out  of  place ;  in  such  a 
case  a  knowledge  of  crayon-drawing  is  brought  to  bear  on 
the  subject.  Colors  for  such  artistic  purposes  exist  in  three 
forms  :  in  cakes,  in  powders,  in  liquids,  in  oil,  and  in  crayons. 

For  touching  up  daguerreotypes,  ambrotypes,  melainotypes, 
and  ferrotypes,  colors  in  very  fine  powder  are  employed. 
These  are  laid  on  the  appropriate  parts,  shaded  off  so  that 
no  sharp  edges  exist,  and  afterward  the  excess  is  blown  off 
with  an  India-rubber  blower,  either  before  the  application  of 
the  varnish  or  afterward,  or  both  before  and  afterward,  as 
in  the  alabastrine  process,  where  the  color  is  laid  on  some- 
times three  or  four  times,  until  it  shows  through  to  the  other 
side. 

Liquid  colors,  that  is,  the  new  Aniline  colors,  are  spe- 
cially adapted  for  the  tinting  and  coloring  of  albumen  na- 
tures ;  these  colors  flow  very  easily,  and  the  albumen  surf  ice 
requires  no  preparation.  For  the  ordinary  photographic 
practitioner  in  card-pictures  they  are  to  be  highly  recom- 
mended. 

Where  the  card-picture  or  photograph  is  to  be  colored, 
hatched  and  stippled  to  perfection  in  the  form  of  a  miniature 
painting,  the  artist  requires  a  complete  outfit  of  Newman's 
photographic  colors,  etc.    It  is  remarkable,  however,  to  see 


THE  CARD-PICTURE. 


225 


with  how  few  colors  the  real  artist  can  execute  the  most  fin- 
ished work. 

The  Colors  used  most  frequently. 
Chinese  white,  Naples  yellow,  raw  sienna,  burnt  sienna, 
yellow  ochre,  yellow  lake,  ivory  black,  bistre,  gamboge,  cobalt 
blue,  Prussian  blue,  indigo,  Chinese  vermilion,  scarlet  lake, 
neutral  tint,  sap  green,  carmine,  rose  madder,  purple  lake, 
Venetian  red,  pink  madder,  and  sepia.  These  are  in  the 
form  of  cakes.  To  these  may  be  added  a  few  bottles  of 
liquid  colors,  as  of  silver  white,  chrome  yellows,  greens,  etc. 

Other  Indispensable  Articles. 
Sable,  fitch,  and  camel's  hair  pencils,  prepared  ox-gall, 
brushes,  shells,  stumps,  slabs,  palettes,  varnish,  gum-arabic, 
gelatine,  penetrating  varnish,  eraser,  basin,  tumbler,  and 
sponge. 

Coloring  of  a  Portrait. 
In  regard  to  coloring  as  to  photography,  I  shall  treat  the 
subject  of  shading  as  divisible  into  three  parts  :  lights,  mid- 
dle tones,  and  shades.  An  irregular  surface  has  always 
these  three  gradations,  not  separated  by  distinct  lines  of 
demarkation,  but  flowing  gradually  or  irregularly  into  one 
another,  according  as  the  undulations  of  the  surface  are  gra- 
dual or  irregular.  Difference  of  distance  in  a  plain  surface 
effects  what  irregularity  effects  on  an  undulating  surface, 
whose  parts  are  nearly  all  at  the  same  distance.  Supposing 
then  a  surface  of  one  and  the  same  uniform  color  gradually 
retires  from  the  eye,  it  is  evident  that  the  nearest  parts  are 
the  most  brilliant  and  light,  the  middle  parts  less  so,  and  the 
most  distant  parts  are  the  darkest  and  least  brilliant.  So  it 
is  also  with  undulating  surfaces,  the  most  prominent  parts 
are  the  lights  or  the  bright  parts ;  the  depressions  or  cavi- 
ties, the  shades  or  darkest  parts;  and  the  retiring  or  interme- 
diate parts  are  the  middle  tones.  This  is  the  effect  of  light 
and  distance,  and  we  have  to  imitate  this  only  in  color  on  a 
plane  surface,  for  the  gradations  of  shade  are  already  im- 
pressed in  the  photograph.  The  question  to  be  solved  then  is 
simply  this  :  there  are  three  differen  t  degrees  of  the  same  color 
in  a  given  space — which  is  the  most  appropriate  manner  of  ob- 
taining this  collocation  or  rather  gradation  of  these  shades 
of  color?  Without  the  slightest  pretension  to  dictate  artist- 
ically on  a  subject  that  takes  much  genius  and  incessant  la- 
bor to  attain  to  perfection,  I  recommend  to  the  photographer, 
who  aims  to  ameliorate  his  photographs  somewhat  respecta- 
bly with  color,  to  lay  on  the  middle  tint  first  over  the  whole 
10* 


226 


THE  CARD-PICTURE. 


surface,  and  then  the  lights  and  shades  afterward,  in  their 
proper  places,  when  the  first  is  dry.  To  be  enabled  to  do 
this,  select  three  gradations  of  the  color  in  question.  It  some- 
times happens  that  the  white  of  the  paper  forms  the  lights ; 
in  this  case  the  dark  parts  may  be  laid  on  and  shaded  off  into 
the  lights. 

Coloring  the  Face. 

Paste  the  photograph  on  a  piece  of  cardboard  in  the  first 
place,  varnish  the  surface  with  Newman's  preparation,  and 
then  proceed  as  follows  :  Lay  on  cobalt  blue  in  small  quantity 
in  all  the  shades  and  depressions  of  the  face  with  a  light  hand 
and  small  pencil,  as,  for  instance,  along  where  the  roots  of  the 
hair  commence,  about  the  temples,  about  the  chin,  beneath 
the  eyebrows,  and  around  the  eyelashes,  etc.  With  another 
pencil  dipped  in  water,  so  as  simply  to  moisten  it,  spread  the 
color  so  as  to  dilute  it  and  shade  it  off,  so  that  it  becomes 
more  and  more  transparent,  until  it  finally  reaches  the  bright 
lights  and  merges  into  them.  You  proceed  in  like  manner 
with  the  interior  of  the  eyes,  that  is,  on  the  visible  parts  of 
the  sclerotic  or  white  of  the  eye.  The  object  of  this  opera- 
tion with  cobalt  blue  is  to  give  more  softness  to  the  dark 
shades  afterward.  The  veins  of  the  hand,  the  borders  of  the 
coat,  waiscoat,  etc.,  and  the  culls  of  the  sleeves  where  they 
terminate  on  the  linen,  have  to  be  treated  in  like  manner, 
beginning  wTith  the  darkest  part  and  shading  off  into  the 
lightest.  Allow  this  color  to  dry,  and  in  the  mean  while  pre- 
pare the  colors  for  the  face,  neck,  hands,  etc. 

For  a  person  of  fresh  complexion  mix  up  a  little  yellow 
ochre,  with  one  third  the  quantity  of  vermilion  and  pink 
lake  in  water  on  the  palette  or  slab,  and  cover  the  face, 
(with  the  exception  of  the  eyes,)  the  arms,  the  hands,  etc., 
with  a  thin  and  uniform  layer  of  this  mixture ;  then  tint  im- 
mediately the  cheek-bones  and  other  prominences  with  a  very 
thin  mixture  of  rose  madder  and  vermilion,  in  order  to  give 
more  animation  to  these  parts  above  the  rest.  If  the  person 
has  a  red  complexion,  these  colors  are  heightened  still  more  ; 
and  where  the  complexion  is  very  pale,  less  vermilion  is  used, 
and  no  color  on  the  cheeks.  The  upper  lip,  being  in  shade, 
must  be  tinted  with  a  mixture  of  cobalt  blue  and  lake,  whilst 
vermilion  is  employed  for  the  lower. 

For  a  sun-burnt  complexion,  add  to  the  colors  indicated  a 
small  quantity  of  bistre,  and  proceed  with  the  general  wash 
as  before  ;  follow  up  with  lake  and  vermilion  for  cheeks, 
where  they  are  colored,  and  use  nothing  where  they  are  pale. 
Where  yellow  prevails  in  the  complexion,  increase  the  ochre. 


THE  CARD-PICTURE. 


227 


Where  a  simply  tinted  picture  is  required,  the  operation  may 
stop  here  ;  but  where  a  higher  finish  is  desired,  you  may  pro- 
ceed and  stipple  in  a  light  tint  of  lake  and  vermilion  on  the 
bright  parts  of  the  cheeks,  lips,  etc.,  by  using  a  very  fine- 
pointed  pencil,  and  filling  up  the  parts  with  contiguous  fine 
dots  or  points  of  color  ;  and  by  hatching  over  the  shadows  on 
the  forehead  and  the  retiring  parts,  the  temples  and  the  chin 
with  a  bluish-gray  color,  that  is,  fill  up  these  parts  with  con- 
tiguous short  lines,  and  then  cross  them  in  a  similar  manner, 
so  as  to  produce  a  greater  depth  of  shade.  Use  a  little  pink 
madder  in  the  corner  of  the  eye  next  the  nose ;  stipple  the 
lips  too,  and  mix  a  little  Chinese  white  with  the  lake  and 
vermilion  for  the  high  lights.  The  edge  of  the  eyelids  have 
to  be  treated  in  a  similar  way.  Stippling  and  hatching  are 
more  especially  required  where  the  colors  have  not  been 
neatly  laid  on  in  the  first  operations.  We  now  proceed  to 
the  hair. 

Blonde  Hair. 

Wash  the  entire  surface  of  the  hair  with  a  mixture  of  yel- 
low ochre  and  bistre  in  small  quantity  ;  then  soften  the  colors 
down  where  they  border  on  the  temples  and  the  forehead 
with  a  pencil  dipped  in  water.  As  soon  as  this  wash  is  dry, 
take  a  very  fine  long  pencil  and  proceed  to  introduce  the 
dark  parts  with  a  mixture  of  ochre  containing  more  bistre. 
The  lights  are  produced  by  adding  either  a  little  white  or 
Naples  yellow  to  the  original  mixture  of  yellow  ochre  and 
bistre.  Both  the  lights  and  shades  are  introduced  by  streaks 
of  color  in  the  direction  of  the  hair,  taking  care  to  avoid  the 
wiry  effect  produced  by  making  each  hair  separately.  Soften 
down  those  parts  that  border  on  the  background,  and  stipple 
up  those  parts  along  the  roots  of  the  hair  with  cobalt  blue  or 
gray,  lest  the  boundary  of  the  hair  should  be  too  marked, 
and  give  it  the  appearance  of  being  inlaid. 

Chestnut- Colored  Hair. 
Cover  the  whole  with  a  layer  of  bistre  ;  then  finish  up  the 
shades  with  a  mixture  of  ivory  black  and  bistre,  the  lights 
with  Naples  yellow  and  bistre,  and  the  high  lights  with  a 
little  white  mixed  with  cobalt. 

Black  Hair. 

The  general  wash  for  such  hair  is  ivory  black  diluted  with 
water ;  the  dark  shades  are  put  in  wTith  ivory  black  of  greater 
consistency,  and  the  lights  with  the  same  color,  mixed  with 
white  and  cobalt  if  the  hair  is  blue-black,  and  with  white  and 
a  little  pink  madder  if  the  hair  is  of  a  pure  black. 


228 


THE  CARD-PICTURE. 


Gray  Hair. 

Cover  the  whole  with  a  mixture  of  equal  quantities  of  bis- 
tre and  white  ;  the  dark  parts  w^ith  bistre  and  a  less  quantity 
of  white ;  the  lights  with  bistre  and  more  white  than  in  the 
general  wash,  and  the  high  lights  with  cobalt,  white,  and 
pink  madder. 

Red  Hair. 

Take  yellow  ochre  and  burnt  sienna  for  the  general  tint ; 
the  same  and  a  little  bistre  for  the  shades ;  white,  yellow 
ochre  and  burnt  sienna  for  the  intermediate  lights ;  white, 
cobalt  and  lake  for  the  high  lights. 

WJiite  Hair. 

The  general  tint  is  that  of  the  photograph  itself ;  the  shades 
are  put  in  with  a  little  black,  and  a  very  small  portion  of 
yellow  ochre  and  cobalt,  and  the  lights  with  Chinese  white. 

The  head  and  face  may  now  be  considered  nearly  finished ; 
all  that  remains  to  be  done  is  to  put  in  the  deep  touches  about 
the  eyes  with  sepia  and  pink  madder,  worked  up  with  a  little 
gum-arabic  ;  those  about  the  nose  are  put  in  with  sepia  and 
gum-water.  Put  in  the  light  in  the  pupil  of  the  eye  with 
Chinese  white.  All  these  final  touches  require  great  care 
and  skill. 

The  hand,  the  neck,  the  shoulders,  etc.,  are  retouched  with 
the  final  stipplings  or  hatchings  in  the  same  way,  in  order  to 
give  animation  to  the  picture,  observing  to  put  in  greys  or 
cobalt  blue  in  the  shades,  and  pink  madder  in  the  bright 
lights. 

Drapery. 

The  handsomest  drapery  is  black.  The  general  wash  is 
ivory  black  of  the  consistency  of  ink.  This  is  laid  on  uni- 
formly with  a  full  pencil,  beginning  at  the  top  and  proceed- 
ing downward  to  the  lowest  edge,  the  picture  being  inclined 
during  this  operation.  All  excess  is  removed  with  a  dry 
pencil,  and  the  layer  is  allowed  to  dry.  When  dry,  the  dark 
shades  are  put  in  with  ivory  black,  of  greater  consistency, 
and  the  lights  with  ivory  black,  mixed  with  Chinese  white 
and  pink  madder. 

In  all  cases  of  tinting  or  coloring  with  any  degree  of  re- 
finement, it  is  indispensable  for  the  beginner  to  be  provided 
with  two  photographs  of  the  model,  one  to  receive  the  color, 
and  the  other  to  serve  as  guide  for  the  introduction  of  the 
shades,  in  case  they  become  obliterated  in  the  general  wash. 


THE  CARD-PICTURE. 


229 


Blue  Drapery. 
The  general  tint  consists  of  Prussian  blue,  or  indigo,  as 
the  case  may  require,  mixed  with  a  little  black  and  pink 
madder ;  the  dark  parts  are  put  in  with  the  same  mixture, 
containing  more  black,  and  the  lights  with  the  same,  con- 
taining an  admixture  of  white.  For  light  blues,  cobalt  blue 
may  be  used  ;  and  the  lights  may  be  obtained  by  proceeding 
with  a  pencil  dipped  in  water  over  the  parts,  so  as  to  remove 
a  portion  of  the  color. 

Green  Drapery. 
Cover  the  dress  with  a  mixture  of  yellow  lake  and  Prus- 
sian blue  ;  and  throw  in  the  shades  with  the  same  color,  mixed 
with  a  little  black  and  pink  madder.  The  lights  are  put  in 
with  emerald  green,  and  the  high  lights  with  this  color,  mixed 
with  a  little  white. 

Red  Drapery. 

The  general  wash  consists  of  vermilion,  mixed  with  a  little 
pink  madder  diluted  with  water.  Add  to  this  a  little  bistre 
or  black  for  the  dark  shades,  and  Naples  yellow  or  white  in 
place  of  bistre  for  the  lights. 

Rose  -  Colored  Drapery. 
Rub  up  pink  madder  with  the  requisite  quantity  of  water 
for  the  general  wash  ;  to  this  add  a  little  black  for  the  shades, 
and  a  little  white  for  the  lights. 

Brown  Drapery. 
Use  burnt  sienna,  with  a  small  portion  of  black  bistre  for 
the  general  tint ;  for  the  shades  add  a  little  black,  and  for 
the  lights  a  little  white. 

Rink  Drapery. 
Cover  the  dress  with  a  dilute  solution  of  pink  madder ; 
then  put  in  the  shades  with  a  mixture  of  pink  madder,  black 
and  cobalt ;  and  the  lights  with  pink  madder  and  Chinese 
white. 

White  Drapery. 
The  general  tint  is  cobalt,  much  diluted ;  yellow  ochre, 
cobalt  and  a  little  black  form  the  shades,  and  Chinese  white 
is  used  for  the  lights. 

Yellow  Drapery. 
Any  of  the  yellows,  as  yellow  ochre,  yellow  lake,  gamboge, 
or  chrome  yellow,  diluted  with  water,  may  be  used  for  the 
ground  color  ;  a  little  bistre  added  to  the  yellow  forms  the 


230 


THE  CARD-PICTURE. 


dark  parts ;  and  a  little  white  to  the  yellow  is  used  to  pro 
duce  the  lights. 

Pearl  Gray. 

Mix  a  little  cobalt,  black  and  pink  madder  for  the  ground 
color ;  add  to  this  Chinese  white  for  the  lights ;  for  the 
shades  use  a  mixture  of  ivory  black  and  cobalt. 

Violet. 

Take  equal  quantities  of  Prussian  blue  and  pink  madder 
for  the  general  wash  ;  white  and  this  mixture  produce  the 
lights  ;  and  neutral  tint  is  used  for  the  shades. 

Background. 

The  background  must  be  secondary  in  effect  to  the  real 
object  in  the  picture  ;  as  a  general  rule,  it  must  be  lighter 
than  the  shades  of  this  object,  and  darker  than  the  lights. 
Avoid  the  appearance  of  inlaying  the  object  or  portrait  in 
the  background.  This  can  be  done  by  the  appropriate  use 
of  shadow,  which  can  be  made  to  throw  the  background  far 
into  the  distance  behind. 

A  similar  uniform  flat  tint  is  laid  on  as  already  described 
for  the  drapery.  Where  defects  exist  in  the  photograph,  a 
general  wash  is  first  laid  on  and  then  pulverized  crayon  of 
the  proper  color  is  rubbed  on  this,  when  dry,  by  means  of 
the  finger,  and  in  those  parts  in  contiguity  with  the  figure 
with  a  fine  stump.  Curtains,  pillars,  tables,  etc.,  are  put  in 
precisely  in  the  same  way  as  drapery  ;  only  be  very  cautious 
not  to  make  these  the  principal  objects  of  the  picture  by 
extreme  definition  and  brilliancy  of  color.  They  must  be 
thrown  into  the  background  by  less  intensity  of  color,  and 
by  a  general  feebleness  of  outline. 

Sow  to  Imitate  Metals,  etc.,  with  Color. 

The  artist  does  not  use  the  metals  themselves  in  miniature 
painting ;  it  would  be  an  insult  to  art  to  request  their  use. 
They  can  all  be  imitated  by  color  as  follows  : 

Gold. — Take  an  equal  quantity  of  yellow  lake  and  yellow 
ochre,  and  a  very  small  quantity  of  burnt  sienna,  and  mix 
them  together  on  the  slab,  and  cover  the  part  desired  with 
this  mixture.  As  soon  as  this  foundation  color  is  dry,  use 
burnt  sienna  alone  for  the  shades.  The  lights  are  formed 
of  chrome  yellow,  and  are  completed  in  the  high  lights  with 
a  little  Chinese  yellow. 

Silver. — Mix  yellow  ochre  and  cobalt  in  equal  quantities 
together  with  a  small  portion  of  ivory  black  ;  this  forms  the 


THE  CARD-PICTURE. 


231 


ground-work.  The  shades  are  made  with  a  little  neutral 
tint  or  ivory  black  ;  and  the  lights  with  Chinese  wThite  laid 
on  with  a  firm  touch. 

Iron. — The  ground-work  consists  of  cobalt  blue,  with 
small  portions  of  black  and  yellow  ochre.  The  shades  are 
made  with  neutral  tint  and  a  small  quantity  of  ochre ;  the 
lights  consisting  of  white,  tinted  slightly  with  black. 

Mother  of  Pearl. — This  substance  takes  light  in  the  pho- 
tograph ;  there  is  no  ground-tone  ;  put  in  a  very  light  tint 
of  cobalt  blue,  as  also  of  very  light  pink  madder  in  two  or 
three  places,  taking  care  they  do  not  come  in  contact ;  the 
shades  are  then  formed  of  black  ochre  and  cobalt ;  and  the 
lights  with  Chinese  white. 

lace,  etc. — Lay  on  a  general  tint  of  ivory  black  somewThat 
deeper  than  that  of  the  dress ;  the  meshes  are  then  intro- 
duced with  white  mixed  with  a  little  blue  and  black.  The 
design  is  finished  by  indicating  it  with  Chinese  white. 

Precious  Stones. — Rubies,  sapphires,  emeralds,  etc.,  receive 
a  foundation  of  neutral  tint  of  considerable  consistency; 
Chinese  white  is  put  on  the  luminous  part ;  whereas  the  re- 
flection, which  is  on  the  opposite  side  to  the  luminous  part, 
receives  the  color  of  the  stone.  The  diamond  alone,  owing 
to  its  nature,  has  a  reflection  of  a  more  dead  white. 

As  soon  as  the  portrait  is  finished,  pass  over  the  eyes,  the 
hair,  the  eye-lashes,  the  nose,  and  the  mouth,  lightly  with  a 
solution  of  gum ;  do  the  same  also  with  satin  stuffs,  such  as 
collars,  waistcoats,  and  robes.  Used  in  moderation,  this  so- 
lution communicates  a  vigor  and  freshness  to  the  picture 
which  are  quite  satisfactory. 

(The  preceding  article  on  tinting  and  coloring  is  extracted 
almost  entirely  from  the  small  work  on  this  subject  by  Hilaire 
David.) 


CHAPTEE  XXXVI. 


DRY  COLLODION  PROCESS— DRY  PROCESSES. 

My  instructions  hitherto  have  been  limited  strictly  to  the 
chemical  and  mechanical  manipulations  that  occur  in  that 
department  of  photography  denominated  the  Wet  Collodion 
Process.  This  process  will  ever  remain  the  predominant 
mode  of  conducting  photographic  operations  in  the  room  ; 
it  is  preferred,  too,  by  many  tourists  in  the  field.  The  in- 
convenience, however,  of  dragging  along  over  mountain  and 
valley,  or  of  stowing  away  on  steamer  or  on  the  cars,  a  com- 
plete miniature  operating  gallery,  has  suggested  the  idea  of 
superseding  all  this  trouble  by  the  discovery  of  a  dry  process. 
Several  processes  have  been  discovered  which  are  more  or 
less  successful,  and  all  very  practical ;  but  it  must  be  con- 
fessed that  the  same  degree  of  sensitiveness  in  the  dry  pro- 
cess has  not  yet  been  attained  as  in  the  wet  process — instan- 
taneous pictures  are  the  result  only  of  the  latter.  It  appears 
natural  for  us  to  expect  such  a  result ;  chemical  combina- 
tions and  reductions  are  effected  most  easily  when  the  mole- 
cules of  matter  are  in  such  a  condition  as  to  have  freedom 
of  locomotion,  by  which  new  molecular  arrangements  can  be 
formed,  in  accordance  with  the  new  electro-chemical  attrac- 
tions and  repulsions  superinduced  by  the  contact  of  dissimi- 
lar bodies. 

For  landscape  and  especially  for  architectural  photogra- 
phy, for  copying,  as  well  as  for  every  case  of  photography  in 
still  life,  where  the  time  of  exposure  is  not  important,  dry 
plates  are  decidedly  superior  to  wet  ones  because  of  the  uni- 
formity of  their  condition  during  the  time  of  their  exposure ; 
wet  plates,  on  the  contrary,  by  desiccation  are  continually 
changing ;  and  one  of  these  changes  —  the  concentration  of 
the  nitrate  of  silver  during  evaporation  —  is  supposed  to  be 
one  of  the  causes  that  produce  minute  apertures  in  the  film, 
and  is  certainly  the  cause  of  an  irregularity  in  the  reduction- 
process  during  development.    The  aim  of  a  dry  plate  is  to 


DRY  COLLODION  PROCESS. 


233 


attain  to  a  maximum  of  preservation  of  the  sensitiveness  for 
an  indefinite  time.  It  has  happened  hitherto  that  the  ratio 
of  this  preservation  is  inversely  as  the  time  of  exposure,  or, 
probably  in  plainer  terms,  that  the  better  the  plate  is  pre- 
served so  as  to  retain  sensitiveness,  the  longer  the  time  re- 
quired to  be  exposed  to  the  actinic  influence  to  produce  a 
given  effect.  The  theory,  that  is,  the  rational  elucidation 
of  the  action  of  reduction  in  a  dry  plate  is  still  a  problem  ; 
if  the  wet  plate,  after  sensitization,  be  thoroughly  washed 
and  then  exposed,  no  picture  is  developed  by  the  reducing 
agent ;  but  in  the  dry  plate  the  film  is  very  carefully  washed 
and  then  coated  with  some  preservative  agent,  as  it  is  called, 
such  as  albumen,  tannic  acid,  gelatine,  honey,  syrup,  infusion 
of  malt,  glucose,  etc.,  and  then  when  otherwise  properly  pre- 
pared and  dry,  it  will  yield,  when  exposed  and  afterward  sub- 
jected to  the  action  of  a  reducing  agent,  an  intense  picture. 
I  say  the  rationale  of  this  phenomenon  is  still  a  problem. 
Some  suppose  that  the  albuminous,  collodio-albuminous,  gela- 
tinous, etc.,  film  becomes  permeable  to  the  developer  in  the 
dry  process ;  whilst  the  collodion  film  in  its  simple  unpre- 
served  condition  is  not  so.  Such  a  supposition  is,  however, 
the  mere  admission  of  our  inability  to  render  any  satisfactory 
explanation ;  it  is  the  admission  of  little  more  than  the  fact 
itself. 

As  yet,  also,  it  is  difficult  to  say  which  of  the  dry  pro- 
cesses in  vogue  is  absolutely  the  best ;  although  perhaps  the 
majority  would  throw  the  weight  of  their  opinion  into  the 
scale  of  the  Tannin  Process  of  Major  Russell.  The  dry  pro- 
cesses most  conspicuously  on  the  carpet  are  :  the  Albumen 
Process  /  the  C olio  dio- Albumen  or  Taupenot  Process  ;  the 
Gelatine  or  Dr.  Hill  Norms'1  s  Process  /  the  Tannin  Process 
of  Major  Pussell ;  and  the  Resin  Process, 

The  Albumen  Process. 
This  process  was  in  use  several  years  before  that  of  collo- 
dion ;  Niepce  de  St.  Victor  first  produced  negatives  with  it. 
It  is  still  employed  by  some  of  the  most  distinguished  artists 
in  Europe  in  the  production  of  stereographs,  both  negative 
and  positive,  also  of  photographs  of  interiors,  and  in  general 
of  pictures  of  still  life.  Its  theory  is  very  simple ;  but  its 
manipulation  demands  great  care  and  skill. 

Formida  for  Iodized  Albumen. 

The  white  of  egg,  10  ounces. 

Iodide  of  ammonium,  44  grains. 

Distilled  water,  (sufficient  to  dissolve  the  iodide.) 


234 


DEY  COLLODION  PROCESS. 


Dissolve  the  iodide  in  the  water,  then  add  the  solution  by 
degrees  to  the  white  of  egg,  entirely  freed  from  the  germ 
and  yolk,  and  beat  the  egg  up  well  with  a  wooden  spatula 
until  it  is  completely  converted  into  froth.  This  operation 
must  be  performed  in  a  place  as  perfectly  free  from  dust  as 
possible ;  and  then  the  albuminous  mixture  is  covered  with 
a  clean  sheet  of  paper  and  put  aside  to  settle  for  a  number 
of  hours.  After  standing  the  required  time,  the  surface  be- 
comes covered  with  a  sort  of  incrustation,  through  which  an 
aperture  is  made  to  allow  the  iodized  albumen  to  flow  out. 
In  some  formulas  for  iodizing  the  albumen,  a  bromide  is 
used  and  a  small  quantity  of  free  iodine. 


Distilled  water,  (sufficient  to  dissolve  the  salts.) 

Beat  up  the  white  of  egg  as  before.  The  operation  is  best 
performed  when  the  temperature  of  the  room  is  low.  A  few 
hours  previous  to  the  operation  of  coating  the  plates,  mop 
the  floor  and  wipe  all  the  shelves  with  a  damp  cloth  —  the 
great  difficulty  in  this  process  is  the  deposition  of  dust  or 
fibers  on  the  glasses  during  the  time  they  are  drying.  An- 
other trouble  (and  these  are  about  all  the  difficulties  the 
operator  has  to  contend  against)  is  the  flowing  of  the  plate 
with  an  even  and  uniform  film,  and  its  uniform  retention  on 
the  plate  until  dry.  The  plates,  of  course,  must  be  perfectly 
clean  in  this  process,  as  in  every  other  for  negative  pur- 
poses. 

Several  methods  have  been  proposed  by  which  the  plate 
can  be  covered  with  albumen,  most  of  which,  no  doubt,  have 
deterred  photographers  from  undertaking  this  branch.  I 
believe  the  best  method  is  to  flow  the  plate  exactly  as  you 
would  cover  it  with  collodion  ;  and  if  the  albumen  ceases  to 
flow  in  certain  parts,  to  use  a  glass  triangle  and  thus  scrape 
it  as  it  wTere  over  those  parts.  It  is  necessary  in  all  cases  to 
pour  upon  the  plate  much  more  albumen  than  you  would 
collodion,  in  order  to  cover  the  plates  easily  and  effectually; 
most  of  the  superfluous  quantity  is  poured  off  at  the  right 
nearest  corner  ;  whilst  the  residual  surplus  is  made  to  tra- 
verse the  plate  diagonally  to  the  farthest  left  corner  and 
then  flow  off  into  the  receiving  vessel.  If  any  surplus  still 
remains  it  is  flowed  gently  toward  the  middle  of  the  plate 


Formula  No*  2. 


The  white  of  egg, 
Iodide  of  potassium, 
Bromide  of  potassium, 
Free  iodine,  .    .  . 


10  ounces. 
44  grains. 
15  grains. 
2  grains. 


» 


DRY  COLLODION  PROCESS.  235 

and  equalized  as  much  as  possible  over  the  whole  surface. 
The  next  operation  is  the 

Drying  Process. 

This  operation,  in  general,  has  been  rendered  very  tedious 
and  inefficient ;  the  plates  were  allowed  to  dry  spontaneous- 
ly, which  occupied  several  hours,  and  in  the  mean  while  the 
albumen  film  became  contaminated  with  the  deposition  of 
dust,  which  completely  spoiled  the  plates.  By  the  following 
method  they  may  be  dried  in  a  few  minutes.  Prepare  a  me- 
tallic table,  that  is,  a  plate  of  iron  or  other  metal  supported 
on  three  legs,  sufficiently  capacious  for  the  purpose.  Be- 
neath this  an  alcohol  lamp  is  kept  burning,  by  which  the 
plate  is  maintained  at  any  given  temperature  by  the  adjust- 
ment of  the  wick,  or  its  distance  from  the  plate.  Next,  sup- 
posing that  stereoscopic  negatives  are  the  objects  of  manipu- 
lation, prepare  a  piece  of  brass  or  iron  longer  and  wider  than 
the  stereoscopic  plate  by  a  quarter  of  an  inch ;  cut  out  from 
this  a  piece  of  the  same  shape  as  the  negative  plate,  but 
shorter  in  its  two  dimensions  by  a  quarter  of  an  inch.  On 
one  end  rivet  a  metallic  handle,  which  may  be  fixed  into  a 
wooden  one.  Turn  up  a  ledge  on  either  side,  as  also  on 
either  end,  (as  far  as  practicable  on  the  nearer  end  by  rea- 
son of  the  handle,)  about  one  tenth  of  an  inch  high.  It  is 
evident  that  so  constructed,  the  negative  can  lie  on  this 
skeleton  plate  and  within  the  ledges.  Place  the  plate,  al- 
bumenized  as  above,  on  this  metallic  plate,  and,  taking  hold 
of  the  handle  with  the  right  hand,  bring  it  into  a  horizontal 
position  over  the  heated  plate  at  a  proper  distance  above  it ; 
equalize  the  albumen  by  inclining  the  hand  as  required ; 
and,  keeping  the  hand  in  continual  motion,  the  film  will  soon 
dry  uniformly,  and  the  plate  can  then  be  put  away  for  future 
use.    So  prepared  it  will  keep  for  an  indefinite  time. 

Sensitizing  the  Film. 

An  oblong  fiat  porcelain  or  glass  dish  is  preferred  to  the 
vertical  bath  for  the  purpose  of  sensitizing  the  film ;  and  if 
the  dish  be  made  twice  as  long  as  required,  it  will  answer 
the  purpose  best. 

Formula  for  the  Sensitizing  Solution. 


Nitrate  of  silver,   1  ounce. 

Acetic  acid,   5  ounces. 

Distilled  water,   10  ounces. 

Iodide  of  potassium,   2  grains. 


236 


DRY  COLLODION  PROCESS. 


Lay  the  albumen  plate  along  one  side  of  the  glass  dish ;  then 
raising  this  side,  pour  into  the  inclined  side  a  sufficient 
quantity  of  the  bath  ;  with  a  dexterous  move  raise  the  in- 
clined side  so  that  the  fluid  may  flow  over  the  albumen  film 
in  one  quick  continuous  layer.  By  this  contrivance  all  lines 
or  marks  of  stoppage  are  avoided.  This  is  a  very  necessary 
provision  here  ;  for  the  slightest  hesitation  or  stoppage  will 
infallibly  show  its  effect  on  the  negative.  About  half  a  min- 
ute will  be  sufficient  to  coagulate  the  albumen,  and  to  sensi- 
tize the  film.  This  operation  is  performed  in  the  dark-room ; 
whereas  that  of  albumenizing  takes  place  in  diffused  light. 
After  sensitization  —  which  occupies  from  thirty  to  fifty 
seconds — the  plate  is  removed  from  the  bath  by  raising  it 
first  with  a  bent  silver  hook,  and  then  seizing  it  by  one 
corner  with  the  hand.  It  is  then  washed  under  the  tap  and 
left  to  soak  in  a  dish  of  distilled  water  until  the  next  plate  is 
prepared.  Finally,  when  it  is  supposed  the  free  nitrate  of 
silver  has  been  thoroughly  removed,  it  is  used  immediately 
or  dried  for  future  use.  The  quantity  of  acetic  acid  in  the 
above  formula  may  be  diminished  in  many  instances  ;  its  ob- 
ject is  to  prevent  fogging,  but  it  diminishes  sensitiveness  at 
the  same  time.  If  with  half  the  quantity  no  fogginess  super- 
venes, this  quantity  will  be  quite  enough ;  by  thus  beginning 
with  a  small  amount  of  acetic  acid,  and  gradually  increasing 
until  fogging  ceases,  more  rapid  effects  may  be  obtained  in 
the  exposure.  When  the  plates  are  kept  long  they  undergo 
a  species  of  decomposition  which  induces  fogginess  ;  the 
fresh  plates,  therefore,  are  in  the  best  condition  for  produc- 
ing normal  results  with  the  greatest  rapidity,  because  the 
sensitizing  bath  requires  the  least  amount  of  acid. 

Blisters  are  apt  to  arise  in  the  film  by  immersion  in  the 
sensitizing  bath,  or  during  the  subsequent  operations.  These 
are  frequently  owing  to  the  imperfect  cleaning  of  the  plates 
or  in  the  clumsy  flowing  of  the  albumen.  Gummy  substances 
are  sometimes  added  to  the  albumen  in  order  to  render  it 
more  adherent  or  less  contractile. 

Exposure  in  the  Camera, 
The  amount  of  exposure  will  depend  on  the  conditions  of 
the  light,  the  focal  length  of  the  lens,  and  the  sensitiveness 
of  the  albumen.  In  the  bright  light  of  spring  an  exposure 
of  two  or  three  minutes  with  a  pair  of  stereoscopic  lenses 
will  in  general  be  amply  sufficient.  Experience  alone  can 
determine  the  amount  of  time  required  in  a  given  case. 


DRY  COLLODION  PROCESS. 


237 


Development  of  the  Image. 
The  plate  is  placed  in  a  glass  dish,  or  in  one  of  gutta- 
percha, and  the  developer  is  poured  upon  it  by  the  same 
mode  of  manipulation  as  just  described  to  be  used  in  the 
sensitizing  operation. 

Formula  for  the  Developing  Solution. 

Gallic  acid,  8  grains. 

Distilled  water,  (warm,  90°,)  2  ounces. 

Previous  to  immersion  in  the  above  solution  the  plates  are 
subjected  to  the  softening  action  of  a  warm  dilute  solution 
of  gallic  acid  (one  grain  to  the  ounce  of  distilled  water)  for 
half  an  hour.  After  this  the  plate  is  flowed  with  a  sufficient 
quantity  of  the  above  solution  containing  five  or  six  drops 
of  a  solution  of  nitrate  of  silver  two  per  cent  strong.  The 
image  will  soon  begin  to  appear,  and  will  proceed  until  the 
vigor  of  the  print  is  satisfactory.  The  development  is  not 
so  soon  complete  as  in  collodion  operations,  the  time  required 
varying  from  a  few  minutes  to  forty  minutes  or  an  hour. 
Any  amount  of  exposure  almost  can  be  made  to  yield  a  good 
picture  by  adapting  the  developing  solution  in  accordance 
with  the  exposure.  If  the  plate  has  been  under-exposed 
more  silver  will  have  to  be  used ;  if  over-exposed,  less  will 
be  found  to  be  all  that  is  necessary.  Silver  from  the  sensi- 
tizing bath  might  be  used,  but  in  this  case  it  must  contain 
more  acetic  acid.  The  weak  solution  above  described  is  to 
be  preferred ;  and  if  there  is  a  tendency  to  fogging,  add  a 
few  drops  of  acetic  acid  to  counteract  the  effect.  As  soon 
as  the  shades  are  sufficiently  dense,  the  plate  is  removed  from 
the  bath,  well  washed  in  many  waters,  and  then  the  image 
is  fixed  in  a  solution  of  hyposulphite  of  soda.  No  varnish- 
ing is  required,  because  the  albumen  film  is  quite  hard  of 
itself. 

Taupenot  Process —  Collodio- Albumen  Process. 
This  process  was  originally  proposed  by  Taupenot.  His 
design  was  to  combine  the  advantages  of  these  two  ingre- 
dients, albumen  and  collodion.  The  collodion  film  on  the 
glass  is  a  much  better  receptacle  of  the  albumen  than  the 
glass  itself;  but  the  operation  is  somewhat  circuitous,  inas- 
much as  the  plate  is  sensitized  twice.  Other  methods  have 
since  been  devised,  in  which  the  collodio-albuminous  film  re- 
quires but  one  sensitization.  Some  of  these  are  found  to  be 
very  effectual  dry  processes. 


238 


DRY  COLLODION  PROCESS. 


Preparation  of  the  Glass  Plates. 
These  are  first  immersed  for  a  number  of  hours  in  the  fol- 
lowing solution  : 

Salts  of  tartar,  1  ounce. 

Rain-water,   16  ounces. 

If  the  plates  have  been  already  employed  before,  soak  them 
in  water  and  remove  the  collodion  film  with  a  piece  of  rag. 
The  alkaline  solution  can  be  used  several  times.  As  soon  as 
the  jDlates  are  removed  from  this  solution,  pass  them  through 
water  several  times,  and  then  clean  and  polish  them  in  the 
vice,  by  means  of  alcohol  and  rotten  stone,  as  previously  di- 
rected. Immediately  before  the  collodion  is  flowed  upon  the 
plate,  it  is  dusted  with  a  silk  cloth,  and  then  with  the  broad 
camel's  hair  pencil.  A  collodion  that  flows  well  and  one 
that  adheres  forcibly  to  the  glass  is  to  be  preferred. 

Formula  for  the  Collodion. 


Ether,  (concentrated,)  12  ounces. 

Alcohol,       "   3  ounces. 

Pyroxyline,  1  drachm. 

Iodide  of  ammonium,   1  drachm. 

Bromide  of  ammonium,  15  grains. 


This  collodion,  containing  quite  an  excess  of  ether,  which 
is  very  volatile,  has  to  be  poured  over  the  plate  with  great 
dexterity.  It  is  very  fluid  and  admits  of  this  dexterity.  The 
plate  is  then,  as  soon  as  the  film  has  sufficiently  congealed, 
immersed  in  the  ordinary  nitrate  of  silver  bath,  containing 
about  35  grains  of  the  nitrate  to  the  ounce  of  distilled  water. 
It  is  left  in  this  bath  for  four  or  five  minutes  and  then  taken 
out  and  allowed  to  drain.  After  this  proceeding,  the  plate 
is  immersed  in  a  dish  of  rain-water  and  well  washed  by  agi- 
tation, or  it  may  be  washed  at  the  tap  in  the  ordinary  meth- 
od, and  then  flowed  with  distilled  water  several  times,  and 
again  allowed  to  drain.  It  is  next  flowed,  while  still  moist, 
Avith  the  following  albuminous  preparation  : 


The  white  of  egg,  (free  from  germs  and  yolk,)        12  ounces. 

Distilled  water,   2  ounces. 

Iodide  of  ammonium,  44  grains. 

Bromide  of  ammonium,  16  grains. 

Ammonia,  1  ounce. 

White  sugar,  2  drachms. 


These  ingredients  are  intimately  mixed  by  an  egg-beater 
until  the  mass  is  reduced  to  froth.  They  are  then  allowed 
to  subside  for  a  day  or  two.  The  clear  part  is  separated  by 
decantation  or  by  a  syringe  from  the  residue  below,  and  from 


DEY  COLLODION  PROCESS. 


239 


the  indurated  scum  on  its  surface  above.  With  this  clear  so- 
lution flow  the  still  moist  plate  as  you  would  with  collodion 
almost.  Holding  the  plate  by  the  left-hand  nearer  corner, 
between  the  thumb  and  the  first  finger,  pour  the  albumen  on 
the  right-hand  further  corner,  then  inclining  the  plate,  let  the 
albumen  flow  to  the  left-hand  further  corner.  Now  allow  the 
whole  body  of  the  albumen  to  flow  down  in  one  mass,  driv- 
ing the  water  before  it  until  it  arrives  at  the  nearest  edge. 
Inclining  the  right-hand  nearest  corner,  allow  the  water  to 
flow  off  together  with  the  excess  or  surplus  of  the  albumen 
into  a  separate  receiver.  Now  raise  the  nearest  edge  of  the 
plate  and  let  the  surplus  proceed  back  again  to  its  place  of 
starting,  and  once  more  to  the  nearest  right-hand  corner, 
when  all  excess  is  allowed  to  flow  off.  The  plates  are  then 
reared  away  on  one  corner  to  dry.  In  this  state  the  film  is 
not  sensitive,  and  consequently  the  plates  so  far  can  be  pre- 
pared beforehand  and  preserved  until  wanted. 

Sensitizing  of  the  Taupenot  Plates. 

Nitrate  of  silver,  1  ounce. 

Acetic  acid,  1  ounce. 

Nitrate  of  silver,  12  ounces. 

The  plates  are  immersed  in  this  bath  with  great  care  and 
dexterity,  in  order  to  avoid  all  lines  of  stoppage,  etc.  In 
thirty  seconds  the  film  will  be  sufficiently  sensitized.  The 
plate  is  then  taken  out  and  plunged  into  a  dish  of  water, 
moved  about  in  this,  then  transferred  to  another,  allowed  to 
drain,  finally  flowed  two  or  three  times  with  distilled  water, 
and  put  away  to  dry  in  a  perfectly  dark  place. 

In  this  condition  the  film  is  much  more  sensitive  to  light 
than  albumen  alone,  although  it  is  less  so  than  collodion.  The 
plates  can  be  preserved  sensitive  for  several  months,  but  the 
sensitiveness  gradually  deteriorates  by  age. 

Exposure. 

With  a  portrait  combination  an  exposure  of  two  or  three 
seconds  will  be  found  to  be  sufficient  to  receive  a  good  im- 
pression of  an  object  well  illumined  by  the  sun,  and  as  many 
minutes  will  suffice  with  a  single  lense. 

Development  of  the  Image. 
The  developing  solution  is  composed  as  follows  : 

Distilled  water,  12  ounces. 

Gallic  acid,   18  grains. 

Pyrogallic  acid,   6  grains. 

Alcohol,  2  drachms. 

Acetic  acid,  •   . .  •    1  drachm. 


240 


DRY  COLLODION  PEOCESS. 


To  every  three  ounces  of  this  solution  add  a  solution  of 
one  grain  of  nitrate  of  silver,  when  about  to  use  it.  A  larger 
proportion  of  pyrogallic  acid  and  nitrate  of  silver  will  in- 
crease the  intensity  of  the  blacks  ;  and  where  the  time  of  ex- 
posure has  been  too  long,  the  gallic  acid  may  be  diminished 
and  the  acetic  acid  increased.  The  horizontal  bath  is  pref- 
erable for  this  sort  of  development.  The  plate,  first  dipped 
in  water,  is  then  lowered  dexterously  with  the  collodio-al- 
bumen  surface  downward  into  the  solution,  and  the  upper 
end  is  allowed  to  rest  on  a  piece  of  glass  or  porcelain,  to  pre- 
vent the  film  from  coming  in  contact  with  the  bottom  of  the 
vessel.  The  plate  is  raised  from  time  to  time  to  watch  the 
progress  of  the  development,  which  may  occupy  from  ten 
minutes  to  twenty-four  hours.  When  the  shades  are  intense 
enough,  the  plate  is  taken  out,  well  washed,  and  then  im- 
mersed in  the  fixing  solution. 

Fixation  of  the  Tanpenot  Plates. 

Hyposulphite  of  soda,  1  ounce. 

Water,  20  ounces. 

Even  a  weaker  solution  will  frequently  be  all  that  is  re- 
quired. The  soluble  iodides  being  removed,  the  plates  are 
taken  out  and  thoroughly  washed  as  usual. 

Modified  Albumen  Process.    {By  James  Larpey) 

Let  the  plates  be  coated  with  any  collodion,  iodized  or 
non-iodized,  and  afterward  well  washed. 

Flow  them  with  the  albumenizing  solution,  which  is  made 
as  follows : 

Formida  for  Iodized  Albumen. 

Albumen,   .    10  ounces. 

Iodide  of  ammonium,  50  grains. 

Bromide  of  potassium,  12  grains. 

Water,  2£  ounces. 

The  mode  of  flowing  is  the  same  as  already  described  for 
the  Taupenot  process.  After  draining,  dry  as  before  indi- 
cated. 

Sensitizing  Solution. 

Nitrate  of  silver,  60  grains. 

Acetic  acid,  60  minims. 

Water,  1  ounce. 

The  time  required  will  be  thirty  seconds  or  thereabouts ; 
remove  from  the  bath  and  wash  thoroughly. 


DRY  COLLODION  PROCESS. 


241 


Exposure. 

This  preparation  requires  about  twice  as  long  an  exposure 
as  wet  collodion. 

Developer. 

Saturated  solution  of  gallic  acid  and  a  few  drops  of  a  so- 
lution of  nitrate  of  silver,  (fifty  grains  to  the  ounce  of  water.) 
By  varying  the  quantity  of  nitrate,  any  kind  of  tone  can  be 
got.  A  small  quantity  yields  brown  tones ;  a  larger  quantity 
black  tones. 

Fixing. 

Wash  thoroughly  and  then  fix  in  the  ordinary  solution  of 
hyposulphite  of  soda ;  finally  wash  and  dry. 

The  collodion  film  in  this  process  facilitates  the  flowing  of 
the  albumen,  which  besides  dries  much  quicker.  Its  keeping 
properties  are  very  good. 

Modified  Collodio- Albumen  Process.     (By  James  3Iudd.) 

Coat  the  plates  with  collodion,  as  usual.  As  soon  as  the 
film  is  sufficiently  adhesive,  immerse  in  the  ordinary  bath  of 
nitrate  of  silver.  Dilute  the  collodion  with  ether  if  it  gives 
a  very  thick  and  creamy  film.  After  sensitizing,  wash  the 
plates  thoroughly,  and  then  immerse  them  in  a  weak  solu- 
tion of  iodide  of  potassium,  (one  grain  to  the  ounce  of  water,) 
for  two  or  three  minutes,  moving  them  gently  all  the  while. 
Wash  again  and  allow  to  drain  for  one  minute. 

Formula  for  Iodized  Albumen. 


Albumen,   10  ounces. 

Iodide  of  potassium,  50  grains. 

Bromide  of  potassium,  10  grains. 

Ammonia,       .  100  minims. 

Water,  2£  ounces. 


First  dissolve  the  iodide  and  bromide  in  the  water,  then 
add  the  ammonia ;  mix  this  solution  with  the  albumen,  and 
beat  the  whole  into  a  froth,  and  then  allow  it  to  settle  for  at 
least  twenty-four  hours.  Decant,  as  previously  directed,  be- 
fore use.  While  the  plate  is  still  wet,  pour  on  the  albumen. 
Pour  it  on  and  off  twice.  Allow  the  plate  to  drain  for  a  few 
minutes  ;  then  dry  it  rapidly  before  a  clear  fire,  and  make  it 
quite  hot. 

Sensitizing  Solution. 


Nitrate  of  silver,   40  grains. 

Glacial  acetic  acid,  -J  drachm. 

Distilled  water,  1  ounce. 

11 

■ 


242 


DRY  COLLODION  PROCESS. 


Warm  the  plate  slightly,  and  then  immerse  it  in  this  solu- 
tion ;  drain  for  a  moment,  and  wash  in  different  dishes  of 
pure  water,  and  finally  under  the  tap.  Dry  the  plates  by 
artificial  heat,  or  let  them  dry  spontaneously. 

Plates  so  treated  are  very  sensitive,  and  possess  tolerable 
keeping  properties.  In  summer,  however,  it  is  advisable  to 
prepare  fresh  ones  every  two  weeks  or  so. 

Development. 

The  plate,  first  moistened  and  supported  on  a  horizontal 
stand,  pour  upon  it  a  fresh  solution  of  pyrogallic  acid,  (three 
grains  to  the  ounce  of  water.)  The  image  will  soon  appear, 
but  it  requires  intensity. 

Intensifying. 

Pyrogallic  acid,  2  grains. 

Citric  acid,  2  grains. 

Nitrate  of  silver  solution,  (20  gr.  strong,)    2  or  3  drops. 

Pour  a  sufficient  quantity  of  the  above  upon  the  plate  and 
keep  it  in  motion.  If  the  shades  do  not  assume  sufficient  in- 
tensity, use  more  silver.  The  solution  may  be  warm  in  cold 
weather,  or  when  the  picture  has  been  under-exposed. 

Fixing  Solution. 

Hyposulphite  of  soda,  6  ounces. 

Water,  16  ounces. 

Wash  the  plates  well  before  immersion ;  fix  as  usual,  and 
again  wash.  Cyanide  of  potassium  must  not  be  used  for  this 
purpose. 

Fothergill  Process. 
This  process,  like  the  two  preceding,  is  a  mere  modifica- 
tion of  the  Taupenot  process,  the  principal  difference  be- 
tween this  and  the  Taupenot  being  that  the  plate  is  sensi- 
tized only  once.  The  plate  is  first  flowed  as  usual  with  any 
ripe  bromo-iodized  collodion,  and  then  as  usual  sensitized  in 
the  common  nitrate  of  silver  bath ;  after  removal  from  the 
bath,  soak  the  plates  in  distilled  or  rain-water,  so  as  to  re^ 
move  all  but  a  mere  trace  of  nitrate  of  silver.  This  part  of 
the  operation  is  probably  the  most  important  and  character- 
istic of  the  operation.  Some  pursue  the  plan  of  soaking  the 
plates,  as  just  directed,  in  a  dish  of  distilled  water,  keeping 
the  water  moving  over  their  surface  until  all  apparent  oily 
streaks  or  greasiness  have  disappeared.  Others  recommend 
a  more  definite  plan.  They  use  a  measured  quantity  of  dis- 
tilled or  rain-water  for  a  certain  number  of  square  inches  of 
surface.    For  a  stereoscopic  plate  half  an  ounce  of  water  is 


DRY  COLLODION  PROCESS. 


243 


poured  carefully  on  one  corner  of  the  plate,  and  is  made  to 
cover  the  whole  quickly,  as  in  the  developing  process.  The 
water  is  then,  kept  in  motion  by  tilting  the  plate  slightly  up 
and  down,  until  the  greasiness  disappears  ;  it  is  then  poured 
off,  and  the  plate  is  allowed  to  drain  for  a  moment,  and  cov- 
ered with  the  following  preservative  solution  : 

Albumen,   2  ounces. 

Ammonia,  20  minims. 

Water,       .    .   6  ounces. 

Mix  well  by  agitation  in  a  large  bottle,  and  filter  through  a 
sponge  immediately  before  use. 

This  solution  is  poured  upon  each  plate  whilst  still  moist, 
in  the  same  manner  as  plates  are  covered  with  collodion ;  the 
residual  quantity  is  poured  off  at  one  of  the  near  corners. 
Another  quantity  of  the  albumen  is  now  poured  upon  the 
plate  and  allowed  to  remain  one  minute,  after  which  it  is 
poured  off,  and  the  plate  is  properly  washed,  drained,  and 
dried  either  spontaneously  or  by  the  application  of  heat. 

Developing  Solution. 
After  exposure,  the  plates  are  first  moistened  in  distilled 
water,  and  then  covered  with  the  following  developer : 

Pyrogallic  acid,  3  grains. 

Citric  acid,  1  grain. 

Water,  2  ounces. 

Alcohol,  10  minims. 

Add  to  each  ounce  of  the  above  solution  half  a  drachm  of 
a  solution  of  nitrate  of  silver,  containing  fifteen  grains  to  the 
ounce  of  water.  "Wash  thoroughly  when  the  image  is  per- 
fect. 

Fixing  Solution. 
Fix  the  impressions  in  a  bath  of  hyposulphite  of  soda ; 
wash,  dry,  and  varnish. 


CHAPTER  XXXVII. 


DR.  HILL  NORRIS'S  PROCESS — GELATINE  PROCESS. 

Make  use  of  a  non-contractile  bromo-iodized  collodion,  and 
after  the  film  lias  been  sensitized  in  the  ordinary  nitrate  of 
silver  bath,  and  allowed  to  drain,  pour  upon  it  a  solution  of 
honey,  containing  one  ounce  of  honey  to  two  ounces  of  dis- 
tilled water.  The  solution  must  be  warmed  and  filtered 
through  filtering  paper,  previous  to  its  application.  This 
solution  may  be  kept  in  vials,  completely  filled,  for  a  con- 
siderable time.  As  soon  as  the  plate  has  been  thoroughly 
covered  with  the  syrup,  it  is  very  carefully  washed  beneath 
the  tap,  until  the  washings  no  longer  taste  either  of  honey 
or  silver.  The  plate  is  next  flowed  with  the  following  solu- 
tion : 

Preservative  Solution. 

Gelatine,  1  drachm. 

Water,  (distilled,)  .........  20  ounces. 

Alcohol,  4  drachms. 

Soak  the  gelatine  in  the  water  until  it  has  swelled,  then  ap- 
ply heat  to  dissolve  it.  After  it  is  cool,  mix  with  the  solution 
the  white  of  an  egg  very  intimately,  then  boil  the  mixture, 
so  as  to  coagulate  the  albumen.  Let  it  stand  for  a  few  mo- 
ments, and  then  filter  whilst  still  hot  through  a  flannel  bag 
before  a  fire.  The  first  portions  of  the  filtrate,  not  being 
clear,  are  poured  back  again  into  the  funnel  and  again  fil- 
tered. The  alcohol  is  next  added  to  the  clear  solution,  in 
order  to  communicate  to  it  keeping  properties. 

When  about  to  use  the  gelatine,  place  the  bottle  that  con- 
tains it  in  a  dish  of  hot  water,  in  order  that  the  gelatine  may 
melt ;  a  separate  vessel  used  for  flowing  the  mixture  is  nearly 
filled  with  the  melted  gelatine,  and  rendered  still  more  hot 
and  fluid  in  a  hot-water  bath.  The  plate  is  first  heated  and 
then  flowed  with  this  hot  solution,  which  is  allowed  to  rest 
upon  the  surface  a  moment ;  fresh  gelatine  is  then  poured 
upon  the  plate,  and  olf  again  at  one  corner,  until  the  film  is 
quite  uniform.    Drain  the  plate  and  dry. 


DR.  HILL  NORRIS'S  PROCESS. 


245 


The  exposure,  developing,  and  fixing  are  the  same  as  in 
the  preceding  processes. 

Dr.  Hill  Norris's  theory  of  this  process  is  as  follows  :  The 
collodion  film,  as  long  as  it  is  moist,  is  a  porous  material,  and 
when  it  is  once  dried,  it  ceases  to  be  porous.  Now,  by 
the  use  of  honey,  gelatine,  etc.,  on  the  moist  surface,  it  is 
supposed  that  these  substances  penetrate  the  pores,  and  thus 
prevent  the  pyroxyline,  during  induration  and  drying,  from 
closing  up  apertures  which  allow  the  developing  solution  to 
permeate  the  film.  The  special  function  of  the  honey,  how- 
ever, seems  to  be  the  removal  of  every  trace  of  nitrate  of  sil- 
ver. 

Tannin  Process  of  Major  Russell. 

This  process  promises  to  supersede  most  of  the  preceding 
dry  methods.  The  collodion  is  apt  to  wrinkle  or  slide  en- 
tirely from  the  plate,  when  prepared  according  to  the  origin- 
al mode.  There  are,  therefore,  two  methods  of  preparing 
the  glass  for  the  reception  of  the  collodion  film. 

In  the  first  place,  and  in  all  cases,  file  the  edges  on  both 
sides  of  each  plate.  Then,  if  the  plate  is  not  first  to  be  covered 
with  a  solution  of  gelatine,  place  it  upon  a  flat  surface,  as  on 
the  corner  of  a  table,  and  laying  a  flat  ruler  along  either  side, 
leaving  one  eighth  of  an  inch  between  the  edge  of  the  glass 
and  the  edge  of  the  ruler,  abrade  the  surface  of  the  glass 
along  this  narrow  strip  by  means  of  a  wet  emery  or  corun- 
dum grindstone,  such  as  is  used  by  dentists.  In  this  way  a 
rough  border  will  be  made  all  round,  to  which  the  collodion 
will  adhere  with  great  tenacity. 

The  plates  must  be  exceedingly  well  cleaned  and  free  from 
all  sorts  of  reduction  from  previous  use.  So  prepared,  they 
may  be  manipulated  without  much  risk  of  undergoing  the 
troubles  alluded  to.  But  it  is  the  opinion  of  many  good 
amateurs  in  this  department,  that  the  plates  work  much  bet- 
ter when  previously  covered  with  a  coating  of  gelatine,  which 
acts  not  alone  as  a  preventive  to  wrinkles,  etc.,  in  the  collo- 
dion film,  but  is  supposed  in  some  way  to  ameliorate  the 
photographic  results  during  development,  with  all  sorts  of 
collodion.  Small  plates  need  scarcely  to  be  covered  with 
gelatine. 

Gelatine  Operation. 
To  prepare  a  clear  solution  of  gelatine,  proceed  as  follows : 
Formula. 

Gelatine,  30  grains. 

Acetic  acid,  (glacial,)  6  minims. 

Water  distilled,  10  ounces. 


246 


DR.  HILL  NORRIS'S  PROCESS. 


Immerse  the  gelatine  in  the  cold  water,  and  let  it  swell  for 
two  or  three  hours  in  a  warm  room ;  after  which  add  the 
acetic  acid,  and  apply  a  gentle  heat  until  the  gelatine  is  dis- 
solved.   To  this  add  the  following  solution : 

Alcohol,  6  drachms. 

Iodide  of  cudmium,  12  grains. 

Bromide  of  cadmium,  3  grains. 

Filter  the  solution  two  or  three  times  through  paper  in  a 
warm  place.  So  prepared,  it  will  keep  a  long  time,  is  limpid, 
and  has,  when  warm,  about  the  ^ame  consistency  as  collo- 
dion, but  it  does  not  flow  over  the  plate  with  the  same  facil- 
ity. 

Warm  the  plates  and  the  gelatine  solution  ;  then  pour  the 
latter  upon  the  surface  of  the  former,  and  cause  it  to  spread, 
either  by  breathing  forcibly  upon  it  or  by  means  of  a  glass 
triangle.  The  sui-jdIus  quantity  is  poured  off  at  one  corner 
into  a  separate  vessel,  and  after  dripping,  the  plates  are  reared 
away  against  the  wall  on  the  same  corner,  upon  bibulous 
paper,  until  they  are  dry.  Spontaneous  drying  in  a  warm 
room  is  preferable  to  drying  quickly  by  artificial  heat.  The 
plates  so  prepared  can  be  preserved  when  dry  in  grooved 
boxes  for  an  indefinite  time. 

Collodion  for  the  Tannin  Process. 
A  good  bromo-iodized  collodion,  already  ripe,  and  of  a 
powdry  nature  is  the  best  for  this  process. 


Formula  for  Collodion. 

Iodide  of  ammonium,   16  grains. 

Iodide  of  cadmium,   8  grains. 

Bromide  of  cadmium,   16  grains. 

Pyroxyline,   48  grains. 

Alcohol,  spec,  grav.,  .805,   4  ounces. 

Ether,  concentrated,   4  ounces. 


After  the  plates  have  been  carefully  flowed  with  this  col- 
lodion, they  are  sensitized  in  a  bath  of  nitrate  of  silver,  made 
slightly  acid  with  acetic  acid,  that  is,  with  one  drop  of  the 
ordinary  acetic  acid  to  each  ounce  of  the  neutral  nitrate  of 
silver  bath.  For  instantaneous  work,  or,  properly  speaking 
here,  for  very  short  exposures,  a  neutral  bath  would  be 
the  most  appropriately  calculated  to  succeed.  When  the 
color  of  the  collodion  film  indicates  a  sufficiency  of  sensitiza- 
tion, which  will  be  in  four  or  five  minutes  under  ordinary 
circumstances,  the  plate  is  taken  out  and  immersed  in  a  dish 
of  distilled  water,  moved  about  for  a  short  time,  and  then 
left  collodion-film  upward  in  the  dish,  until  a  second  plate  is 


DR.  HILL  NOKRIs's  PROCESS. 


247 


collodionized  and  sensitized.  It  is  then  thoroughly  washed 
under  the  tap  with  common  water,  and  finally  flowed  with 
distilled  water. 

Preservative  Solution  of  Tannin, 
This  solution  may  vary  in  strength  from  ten  to  thirty  grains 
of  tannin  to  one  ounce  of  water,  depending  upon  the  light 
and  the  nature  of  the  collodion. 

Tannin,  15  grains. 

Distilled  water,   1  ounce. 

Dissolve  and  filter  through  paper  before  use,  and  then  add 
four  or  five  minims  of  alcohol  to  the  ounce  of  water,  but  al- 
ways after  filtration.  Of  this  solution  pour  first  a  small  quan- 
tity upon  the  plate,  so  as  to  remove  before  it  all  superfluous 
water ;  pour  it  on  and  off  two  or  three  times,  and  afterward 
commence  wTith  a  fresh  solution.  Allow  the  plate  to  drain 
for  a  minute  or  two,  then  rear  it  up  on  end  upon  a  piece  of 
blotting  paper,  and  afterward  dry  spontaneously  or  by  ar- 
tificial heat,  remote  from  all  light.  When  perfectly  dry,  the 
plates  will  keep  in  the  dark  for  a  long  time. 

When  the  contrasts  of  the  landscape  are  very  marked,  and 
the  light  brilliant,  a  less  quantity  of  tannin  maybe  used;  the 
greater  the  quantity  of  tannin,  the  greater  the  density  of  the 
shades.  When  the  plates  are  dry,  the  film,  if  in  a  right  con- 
dition, will  be  bright  and  highly  polished  in  its  appearance. 

If  the  tannin  plates  have  not  first  been  covered  with  a  so- 
lution of  gelatine,  this  is  the  time,  before  they  are  put  away, 
to  proceed  round  the  edges  of  the  film  with  varnish.  This 
operation  can  be  performed  best  by  dipping  the  quill  end  of 
a  strong  feather  from  a  hen's  wing  into  the  varnish,  and  then, 
inclining  the  feather,  begin  at  one  corner  of  the  plate  in  con- 
tact with  the  edge  and  proceed  to  the  other  end  slowly,  so 
that  a  small  quantity  of  the  varnish  is  attracted  by  the  col- 
lodion film  as  you  advance.  The  side  of  the  quill  is  in  con- 
tact with  the  edge,  and  not  the  end.  As  soon  as  the  varnish 
is  thoroughly  dry,  the  plates  are  stored  away.  It  is  best  to 
use  the  plates  as  soon  after  preparation  as  possible. 

The  time  of  exposure  is  three  or  four  times  as  long  as  with 
the  wet  process,  but  this  may  be  shortened  by  following  the 
plan  of  development  recommended  by  Dr.  Draper. 

Development. 

v    1      (  Pyrogallic  acid,  72  grains. 

J>0-  *'     (  Alcohol,  1  fluid  ounce. 

Filter  if  there  is  any  turbidity,  otherwise  not. 


248 


DR.  HILL  NORRIs's  PROCESS. 


(  Nitrate  of  silver,   20  grains. 

No.  2.    4  Citric  acid,  20  grams. 

(  Distilled  water,  1  ounce. 

Filter  if  there  is  a  white  precipitate,  otherwise  not.  With 
No.  1  and  No.  2  as  stock  bottles,  proceed  as  follows  : 

Dilute  solution  of  (  Solution  No.  1,   .    .    .    1  drachm.  )  ™  . 

No.  1.         \  Distilled  water,    .    .    .  G  ounces.  J       present  use. 

Of  this  dilute  solution  of  No.  1,  take  out  four  drachms  for  a 
stereoscopic  slide,  and  add  to  it  from  fifteen  to  twenty-five 
minims  of  No.  2.  This  mixture  is  made  immediately  before 
the  plate  is  to  be  developed. 

Immerse  the  dry  plate  for  a  few  seconds  in  distilled  water ; 
then  pour  on  the  developer  and  keep  it  in  motion  until  the 
image  appears.  If  the  picture  is  slow  in  making  its  appear- 
ance, although  the  sky  develops  quickly,  the  time  of  exposure 
was  too  short,  and  the  developer  must  be  increased  in  strength, 
by  adding  ten  or  fifteen  drops  of  No.  1.  On  the  contrary, 
where  the  time  has  been  too  long,  the  development  on  all 
parts  will  be  simultaneous,  and  the  proper  equilibrium  of  ac- 
tion will  have  to  be  maintained  by  adding  a  few  drops  of  No. 
2,  otherwise  the  sky  will  not  be  opaque  enough. 

Dr.  Draper's  modification  consists  in  immersing  the  plates 
after  exposure  in  a  vessel  of  hot  distilled  water,  and  then 
proceeding  as  above.  The  development  is  very  rapid.  In 
consequence  of  this  the  time  of  exposure  can  be  reduced  al- 
most to  instantaneity. 

It  is  advisable  not  to  postpone  the  development  long  after 
the  exposure  ;  during  the  evening  of  the  day  on  which  the 
pictures  were  taken  is  in  all  respects  an  appropriate  time  for 
the  development,  and  although  in  many  instances  this  opera- 
tion can  be  put  off,  it  is  not  advisable.  The  color  of  the 
image  by  the  tannin  process  is  rich  and  warm  ;  its  tone  is 
very  agreeable.  Plates  prepared  either  by  this  process  or 
by  the  albumen  are  well  adapted  for  taking  transparent  pos- 
itives, by  direct  contact  printing,  for  the  magic  lantern,  or 
for  the  stereoscope. 

The  developed  plates  are  well  washed  and  fixed  in  a  bath 
of  hyposulphite  of  soda,  but  not  of  the  cyanide,  because  it  is 
apt  to  loosen  the  film.  They  are  then  carefully  washed,  so 
as  not  to  disturb  the  film,  dried  and  varnished. 

The  Tannin  and  Honey  Process. 
Several  modifications  of  the  Tannin  process  have  been  pro- 
posed, more  or  less  successful ;  the  honey  process  of  Mr.  Eng- 
land being  one  which  seems  to  possess  considerable  advan- 


DR.  HILL  NORRIs's  PROCESS. 


249 


tages  in  sensitiveness.  Mr.  England's  formula  for  collodion 
is  as  follows : 

To  five  parts  of  ether  and  three  of  alcohol,  add  sufficient 
pyroxyline  to  give  a  tolerably  thick  film.  As  soon  as  it  has 
well  settled,  decant  the  clear  supernatant  part  into  another 
bottle,  and  measure  off  two  portions  of  ten  drachms  each  ; 
to  one  add  forty  grains  of  bromide  of  cadmium,  and  to  the 
other  thirty  grains  of  iodide  of  ammonium ;  shake  till  dis- 
solved, and  put  by  to  settle.  When  thoroughly  settled,  add 
one  drachm  of  each  to  six  parts  of  plain  collodion. 

Sensitize  in  a  neutral  bath  of  nitrate  of  silver,  containing 
forty  grains  of  nitrate  of  silver  to  the  ounce  of  wTater,  and 
wash  afterward  in  a  dish  of  distilled  water,  rendered  acid  by 
acetic  acid.  The  plate  is  left  in  this  dish  until  a  second  one 
is  prepared ;  it  is  then  taken  out  and  washed  thoroughly  be- 
neath the  tap,  flowed  with  distilled  water,  and  coated  with 
the  following  solution : 

Tannin,  15  grains. 

Honey,  15  grains. 

Distilled  water,  1  ounce. 

Coat  as  before  directed,  wash  and  dry.  Protect  the  edges  of 
the  film  with  varnish. 

After  exposure,  immerse  the  plate  in  a  bath  of  nitrate  of 
silver,  ten  grains  to  the  ounce,  as  follows : 


Keep  the  plate  in  this  bath  for  one  minute,  and  then  develop 
with  the  pyrogallic  acid  developer  as  usual,  or  according  to 
the  method  in  the  Tannin  process  just  described. 

Mr.  Anthony,  of  New-York,  finds  it  advantageous  to  fume 
the  Tannin  plates  for  a  few  seconds  with  the  vapor  of  am- 
monia, for  instance,  the  evening  before  their  exposure,  the 
time  of  which  is  said  to  be  shortened  by  this  process. 


This  is  the  simplest  of  all  dry  processes,  the  discovery  of 
Despratz.  It  consists  simply  in  dissolving  in  the  collodion 
about  two  and  a  half  grains  of  powdered  resin  for  every 
ounce  of  collodion.  After  sensitization  the  plate  is  well 
washed  and  dried.  The  development  and  all  other  manipu- 
lations are  the  same  as  in  the  wet  collodion  process.  Dubosq 
makes  use  of  amber,  and  Hardwich  of  Glycirrhizine  for  the 
same  purpose. 


Nitrate  of  silver, 
Distilled  water, 
Acetic  acid, 


2  drachms. 
12  ounces. 
1  drachm. 


Resin  Process. 


11* 


250 


DR.  HILL  NORRIs's  PROCESS. 


Sutton'*  s  Rapid  Dry  Process. 
The  operations  in  this  process,  as  furnished  by  Sutton,  are 
as  follows : 

1.  Clean  the  glass  plate,  dry  it  thoroughly,  and  apply  to 
it  a  solution  composed  of  one  grain  of  India-rubber,  dissolved 
in  an  ounce  of  keroselene. 

2.  Coat  the  plate  thus  prepared  with  bromo-iodized  collo- 
dion, containing  an  equal  number  of  atoms  of  iodine  and  bro- 
mine, added  in  combination  with  cadmium.  There  should 
be  about  five  grains  of  mixed  iodide  and  bromide  of  cadmium 
to  the  ounce  of  collodion. 

3.  Excite  the  film  in  a  bath  composed  of  thirty  grains  of 
pure  recrystallized  nitrate  of  silver,  slightly  acidified  with 
nitric  acid. 

4.  Wash  off  all  the  free  nitrate  of  silver,  and  pour  over  the 
film  a  preservative  composed  of  twenty-five  grains  of  gum- 
arabic  freshly  dissolved  in  an  ounce  of  water.  Let  it  dry 
spontaneously,  and,  before  putting  the  plate  into  the  dark- 
slide,  dry  it  again  thoroughly  before  a  hot  flat-iron. 

5.  Give  the  same  exposure  as  for  wet  collodion. 

6.  Develop  the  picture  by  first  wetting  it  with  distilled 
water,  and  then  pouring  over  it  a  developer,  consisting  of 
one  ounce  of  distilled  water,  two  grains  of  pyrogallic  acid, 
two  scruples  of  glacial  acetic  acid,  and  a  few  drops  of  a  weak 
solution  of  nitrate  of  silver.  The  image  appears  immediately, 
and  very  soon  acquires  the  necessary  intensity. 

7.  Fix  the  negative  in  the  usual  way,  with  a  saturated  so- 
lution of  the  hyposulphite  soda  or  lime,  and  when  dry,  var- 
nish it  with  spirit  varnish. 

Keene*s  Rapid  Dry  Process. 

This  is  a  modification  of  the  Tannin  Process,  or  Tannin 
and  Honey  Process.  The  characteristic  difference  is  this : 
After  the  plate  is  sensitized,  it  is  not  washed,  but  flowed  im- 
mediately with  equal  parts  of  a  filtered,  fifteen  grain  per 
ounce  solution  of  tannin  and  gum,  the  latter  consisting  of 
four  ounces  of  picked  gum-arabic,  dissolved  in  eight  ounces 
of  rain-water.  The  collodion  plate  requires  twice  the  time 
in  the  nitrate  bath  of  an  ordinary  collodion  plate.  When  re- 
moved from  the  bath,  drain  a  few  moments  and  flow  it  with 
the  preservative  mixture  bountifully,  as  with  collodion,  tilt- 
ing the  plate,  so  that  the  tannin  solution  flows  from  the  right 
upper  corner  to  the  left  upper  corner,  then  to  the  left  lower 
corner,  and  finally  to  the  right  lower  corner,  and  then  along 


DR.  HILL  NORRIS'S  PROCESS. 


251 


with  the  excess  of  water  off  at  this  corner.  Repeat  the  opera- 
tion once  or  twice.  The  last  lot  can  be  used  for  the  first  of 
the  next  plate.  The  plate  is  then  drained,  washed  and  dried. 
It  is  said  to  be  almost  as  sensitive  as  a  wet  collodion  plate. 
It  is  soaked  in  distilled  or  rain-water  before  it  is  developed. 
It  is  fixed  and  developed  like  any  other  tannin  plate. 


CHAPTER  XXXVin. 


PRINTING  OF  TRANSPARENT  POSITIVES  BY  THE  DRY  PROCESS. 

Positives  on  glass,  whether  for  the  stereoscope  or  the  magic 
lantern,  that  is,  such  as  are  to  be  regarded  by  transmitted 
light,  are  prepared  most  easily,  most  quickly,  and  most  effect- 
ually by  the  Dry  Process.  The  first  part  of  the  operation 
consists  in  obtaining  a  correct  negative  of  the  object,  either 
by  the  wet  or  the  dry  process,  the  latter  being  preferable, 
because  the  negative  so  obtained  is  less  liable  to  be  damaged 
m  the  subsequent  manipulations  than  the  ordinary  unvar- 
nished collodion  negative.  The  negative  in  question  is  re- 
quired to  be  very  sharp  in  all  its  parts,  moderately  dense  in 
the  deepest  shades,  though  not  so  much  so  as  for  the  ordinary 
printing  on  paper,  and  transparent  in  the  lights.  The  film 
must  be  thin,  bright,  and  free  from  all  deposit  of  dust  arising 
from  reduction  or  impurities.  The  negative  best  adapted 
for  the  printing  of  glass  transparencies  is  incontestably  that 
with  albumen  ;  for  it  requires  no  varnish,  and  is  endowed 
with  all  the  requisites  above  mentioned.  The  albumenized 
glass,  too,  is  the  best  for  the  reception  of  the  transparent  image. 
Dry  plates  by  the  Tannin  Process  are  the  next  best ;  it  is  a 
good  plan  in  this  instance  also  to  have  the  negative  an 
albumen  print,  and  the  transparencies  on  tannin  plates. 

Provided  with  such  a  negative,  place  it  in  the  shield  of 
the  plate-holder  with  the  image  toward  you  ;  on  this  place 
a  sensitized  tannin  or  albumen  plate,  the  film  being  from  you, 
so  that  the  two  films  lie  in  intimate  juxtaposition  ;  close  the 
door,  whose  spring  retains  the  plates  firmly  in  contact.  In- 
troduce the  plate-holder  into  the  grooved  receptacle  at  one 
end  of  the  cylinder,  as  described  in  a  previous  chapter  of  this 
work,  expose  the  other  end  to  the  light  of  a  cloud,  etc.,  and 
draw  the  slide.  An  exposure  of  a  few  seconds  will  be  all- 
sufficient.  The  precise  time  can  not  be  accurately  given,  but 
is  easily  ascertained  with  given  materials.  Begin  with  an 
exposure  of  one  second,  and  proceed  until  you  find  the  time 
best  adapted  for  the  circumstances.    With  dry  plates,  it  is 


PRINTING  BY  THE  DRY  PROCESS. 


253 


not  absolutely  necessary  to  use  the  cylinder ;  the  cylinder, 
however,  yields  superior  results. 

The  development  of  the  plate  depends  upon  the  nature  of 
it  s  constitution  ;  if  an  albumen  plate,  develop  it  accordingly  ; 
if  a  tannin  plate,  in  like  manner.  These  different  modes  are 
given  in  detail  in  the  preceding  chapters  on  the  subjects  in 
question  ;  as  well  as  every  other  information  referring  to  the 
completion  of  the  picture  after  development,  such  as  wash- 
ing, fixing,  drying,  and  varnishing. 

The  color  of  an  albumen  print  is  not  sufficiently  agreeable 
for  stereoscopic  purposes.  This  color  is  improved  by  im- 
mersing the  plate  in  the  first  place  in  a  dilute  solution  of 
bichloride  of  mercury,  and  after  it  has  been  washed,  in  a 
solution  of  sel  (For,  (the  double  hyposulphite  of  gold  and 
of  soda,)  when  the  color  will  be  an  agreeable  sepia  tone. 

Chloride  of  gold  alone,  in  dilute  solution,  communicates  to 
the  fixed  positive  an  agreeable  purple  tone ;  naturally  the 
prints  have  to  be  washed  always  after  such  operations. 

To  take  Copies  of  any  given  size. 

Where  the  required  transparency  must  be  of  a  given  size, 
as  is  the  case  in  the  preparation  of  slides  for  the  magic  lan- 
tern, and  for  other  similar  exhibitions,  or  for  church  win- 
dows, the  printing  has  to  be  performed  in  the  camera  and 
by  means  of  the  lens.  This  process  is  described  in  a  pre- 
ceding chapter  of  this  work. 

Theoretically  a  picture  can  be  made  as  many  times  larger 
or  smaller  than  the  original  by  an  analysis  of  the  well-known 
formula  for  the  conjugate  foci  of  a  double  convex  lens.  This 
formula  is  as  follows : 

1  _  1  1_ 

V  ~  f  u 

where  the  thickness  of  the  lens  is  not  taken  into  consider- 
ation ;  but  with  this  consideration,  the  formula  will  be  : 

1  =  1    •    1       tlp-1  _  1  V 
v      f       u      p\     r         u  r 

when  any  two  of  the  preceding  terms  v,f,  and  are  known, 
the  third  can  be  found ;  f  signifies  the  principal  focal  dis- 
tance ;  u  the  distance  of  the  object  from  the  nearest  surface 
of  the  lens ;  v  is  the  distance  of  the  picture  on  the  ground 
glass  fr  om  the  same  surface  5  t  is  the  thickness  of  the  lens  1 
r  the  radius  of  curvature  of  the  first  surface ;  and  p  is  the 
index  of  refraction  of  the  transparent  medium  of  which  the 
lens  is  formed. 


254 


PRINTING  OF  TRANSPARENT  POSITIVES  * 


Without  going  into  a  minute  optical  discussion,  I  will 
analyze  the  first  formula  so  as  to  be  enabled  with  a  lens  of  a 
given  power,  and  with  a  given  sized  object  to  show  what 
must  be  the  respective  distances  of  the  object  and  image 
from  the  lens. 

In  the  first  place  I  will  explain  a  few  technical  terms, 
such  as  the  axis  of  a  lens,  the  optical  center  of  a  lens,  the 
principal  focus  of  a  lens,  the  conjugate  foci  of  a  lens,  the 
equivalent  focus  of  a  combination. 

The  axis  of  a  lens  is  a  line  perpendicular  to  all  the  diam- 
eters drawn  from  edge  to  edge. 

The  optical  center  of  a  lens  is  the  point  where  a  line  (join- 
ing an  impiftgent  and  an  emergent  ray  that  are  parallel  to 
each  other)  crosses  the  axis ;  this  center  is  sometimes  within 
the  lens,  sometimes  on  its  surface,  and  sometimes  external 
to  it. 

The  principal  focus  of  a  lens  is  the  point  where  parallel 
impingent  rays  converge  and  cross  after  refraction  and 
emergence ;  it  is  the  burning  point  of  the  sun's  rays.  The 
distance  of  this  point  to  the  optical  center  is  called  the  prin- 
cipal focal  distance. 

The  co?ijugate  foci  are  any  point  on  an  object  and  its  cor- 
responding point  on  the  image.  The  distances  of  these  two 
points  to  the  optic  center  are  denominated  conjugate  focal 
distances  ;  these  distances,  however,  are  generally  reckoned 
from  the  vertex  or  surface  of  the  lens  next  to  the  object. 

The  vertex  is  that  point  where  the  axis  touches  the  sur- 
face of  the  lens  nearest  the  object. 

The  equivalent  focus  is  a  term  that  refers  to  compound 
lenses,  such  as  those  used  by  the  photographer;  it  is  the 
principal  focfics  or  the  focus  of  parallel  rays  of  the  combin- 
ation. It  is  called  equivalent  from  being  compared  with  a 
single  lens  that  will  produce  the  same  sized  picture  at  the 
same  distance  of  the  object.  If  rays  from  an  object  impinge 
upon  a  lens  and  on  emerging  converge,  they  will  cross  each 
other,  and  where  they  cross  they  will  form  a  picture  of  the 
object. 

The  axis  of  a  radiant  point,  that  is,  of  any  point  on  an 
object,  does  not  mean  the  same  thing  as  the  axis  of  the  lens; 
it  is  a  line  that  is  broken  at  the  two  surfaces  of  the  lens, 
passing  through  the  optic  center,  of  which  the  impingent 
and  emergent  parts  are  parallel.  On  this  axis  the  image  oi 
the  object  is  found.  If  rays  emerge  parallel,  they  wall  never 
cross,  and  therefore  produce  no  picture;  if  they  diverge 


BY  THE  DRY  PROCESS. 


255 


after  emergence,  the  image  will  be  on  the  same  side  of  the 
lens  with  the  object,  and  is  denominated  a  virtual  image. 

Equidistant  conjugate  focus  refers  to  an  object  and  its 
image  on  the  ground  glass  when  they  are  equidistant  from 
the  optical  center,  or  more  intelligibly  speaking  for  the 
photographer,  wThen  the  image  and  the  object  are  of  the 
same  size.  The  distance  of  the  equidistant  conjugate  focus 
can  be  derived  from  the  principal  focal  distance,  or  vice 
versa.    Thus  in  the  equation  : 

11  1 

v  ~~  f  ~  u 

let  f=12  inches,  required  the  value  of  v  and  u  when  they 
are  equal,  or  when  the  picture  and  object  with  the  lens  in 
question  are  of  the  same  magnitude  ?    By  transposition 

1      1      1       2  12 

— 3T=  h  —  or  -r7r=  or  #=24  inches. 

f      «       v       v        12  v 

Therefore  if  a  given  single  lens  has  a  principal  focus  of 
12  inches,  the  ground  glass  as  well  as  the  object  will  have 
to  be  placed  respectively  at  a  distance  of  24  inches  from  the 
lens  in  order  to  obtain  a  picture  of  the  same  size  as  the 
object. 

The  principal  focal  distance  of  a  single  lens  can  be  found 
with  sufficient  accuracy  for  all  practical  purposes  by  measur- 
ing the  distance  of  the  lens  from  the  burning  point,  and  by 
adding  to  this  distance  half  the  thickness  of  the  lens. 

The  principal  focal  distance  of  a  combination  can  be 
found  w^ith  the  same  degree  of  accuracy  by  adjusting  the 
camera  before  a  given  line  so  that  the  image  of  the  line  on 
the  ground  glass  is  exactly  of  the  same  size.  One  fourth 
of  the  distance  between  the  object  and  the  image  is  the 
principal  focus  required.  For  instance,  let  this  distance  be 
48  inches,  then  v  is  24  and  u  is  24  inches ;  by  substitution 

11121 
T=  24  +  ^4  =  24  =12'  °r/=12  mcheS* 

The  distance  of  either  the  image  or  the  object  from  the 
optical  center  bears  a  direct  ratio  with  the  size  of  the  image 
or  the  object,  whether  the  lens  be  single  or  compound. 
Thus  then,  if  we  know  the  respective  linear  magnitudes  of 
the  image  of  the  same  object  as  obtained  by  two  single 
lenses  or  by  a  single  lens  and  a  combination,  as  well  as  the 
principal  focal  length  of  the  former,  (which  can  always  be 
easily  obtained  by  the  sun's  rays,)  we  can  by  the  legitimate 


256 


PRINTING  OF  TRANSPARENT  POSITIVES 


proportion  derive  the  principal  focits  of  the  other  single 
lens  or  the  equivalent  focus  of  the  compound  lens.  For  in- 
stance, let  the  principal  focal  length  of  a  single  lens  be  3 
inches,  and  the  linear  magnitude  of  an  image  of  a  given 
object  be  2  inches  as  obtained  by  this  lens ;  let  also  5  inches 
be  the  linear  magnitude  of  the  image  of  the  same  object  at 
the  same  distance  when  taken  by  another  lens  ;  required 
the  principal  focal  length  of  the  other  lens,  (if  single,)  or 
the  equivalent  focal  length  of  the  combination  ? 

L.M.     P.F.      L.M.  INCHES. 

By  proportion  as  2  :  3  :  :  5  :  7J  the  principal  focal  length  required. 

In  the  proportion  -— r-=-^--f--^-,  let  u  be  n  times  larger  than  v ; 
required  the  proportion  that  /bears  to  u  f 

1       1       1     nv  +  v    n  +  1 
f       v      nv      nv2       nv  °r 
nv=f     +      but  u—nv 
.-.  u=f  (n  +  1)  and 
t?=/fo  +  l) 
n 

Hence  if  we  multiply  the  principal  focal  length  of  any 
lens  by  one  more  than  the  times  the  image  is  linearly  greater 
than  the  object,  we  shall  obtain  the  distance  the  screen  is  to 
be  placed  from  the  lens ;  and  if  we  divide  this  latter  pro- 
duct by  the  number  of  times  the  image  is  linearly  greater 
than  the  object,  we  obtain  the  distance  of  the  object  from 
the  lens.  In  these  analytical  conclusions  we  suppose  the 
lens  to  be  single  and  very  thin.  The  deductions  thus  de- 
rived have  to  be  regarded  in  reference  to  the  center  of  the 
combination.  The  following  table  has  been  constructed  in 
accordance  with  the  preceding  principles,  and  it  exhibits 
the  distances  between  the  object  and  the  lens,  the  image 
and  the  lens,  and  the  object  and  the  image.  Any  degree  of 
reduction  and  enlargement  with  a  given  lens  or  combination, 
whose  equivalent  focus  is  known,  can  be  effectuated  with 
great  ease  by  adjusting  the  object  and  the  ground  glass  at 
the  distances  indicated. 

0  in  the  following  table  stands  for  the  distance  between 
the  object  and  the  center  of  the  combination. 

1  stands  for  the  distance  between  the  image  and  the  center 
of  the  combination. 

S  stands  for  the  distance  between  the  object  and  the 
image,  or  the  sum  of  the  two  preceding. 


* 

GO 

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* 

* 

CO 

# 

"I 

1  * 

ft 

porno 

cor-'p 

co.-p 

popnp 

po.wp 

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cor-p 

GO 

M.-ip 

If 

sss 

§55 

igS5 

§S5 

- 

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■ 

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HI 

|fa 

HI 

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fai 

fai 

Ifa 

5»5 

fal 

fa* 

fa# 

ss* 

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fa- 

fa» 

6S§ 

fa» 

§coS2 

fas 

4s8 

faS 

£*.5 

fag 

fa» 

00  bO  OS 

3fa 

III 

fas 

fa§ 

fai 

fa" 

fai 

fa" 

fai 

fa.7 

fa  a 

fa? 

fas 

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fa» 

fa» 

faS 

1*8 

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fa- 

fa- 

fa* 

fas 

£»S 

fas 

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ij 

6-*fc 

fa" 

fa" 

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fa- 

If 

fa- 

fa! 

Ufa 

fa» 

$** 

fas 

If* 

Is* 

fas 

fa* 

fa- 

ifa 

fa  5 

fa5 

III 

fas 

fas 

fa» 

fa- 

fa* 

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If 

fas 

If 

fa»| 

is* 

fas 

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ffa 

fas 

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fa  « 

fa> 

ffa 

fa" 

fa  § 

fa- 

Jfa 

fa" 

fas| 

4 

BY  THE  DRY  PROCESS, 


257 


Application  of  the  Preceding  Table. 

If  the  equivalent  focus  or  principal  focal  length  of  a  com- 
bination be  known,  it  is  very  easy  to  arrange  the  object  to 
be  photographed,  the  camera  and  the  screen,  so  as  to  produce 
a  picture  so  many  times  larger  or  smaller  than  the  object,  as 
may  be  required  ;  for  instance,  let  the  focal  length  of  the 
combination  be  4|  inches,  what  must  be  the  conditions  of 
the  three  things,  object,  combination,  and  ground  glass,  so 
as  to  obtain  an  image  eight  times  larger  than  the  object  ? 

Look  for  4£  in  the  first  vertical  column,  and  for  8  on  the 
first  horizontal  line ;  where  these  two  columns  meet  will  be 
found  all  that  is  required.  In  the  first  place  the  object  and 
the  ground  glass  must  be  45T9g  inches  apart,  the  ground  glass 
is  40|-  inches  from  the  middle  of  the  combination,  and  the 
object  is  consequently  5T\  inches  from  the  same  point. 

If  we  wish  to  diminish  the  size  of  the  picture  eight  times, 
then  the  two  latter  of  the  above  terms  are  inverted,  the  ob- 
ject being  45T9g  from  the  center  of  the  combination,  and  the 
image  only  5^  inches  from  the  same  point. 

The  table  can  be  extended  as  far  as  desired,  by  using  the 
multiples  of  the  numbers  already  given.  If  we  required  the 
conditions  for  15  inches  focus,  multiply  those  along  column 
5  by  3,  the  results  will  be  the  conditions  required. 

Microplwtography  and  Macrophotography. 
This  branch  comprehends  the  mode  of  taking  photographs 
of  microscopic  or  almost  invisible  objects,  as  also  of  amplifi- 
cation by  means  of  the  solar  camera.  In  either  case  means 
are  resorted  to  by  which  light  can  be  concentrated  or  con- 
densed on  the  object  or  collodion  positive  to  be  copied,  and 
enlarged  or  diminished.  These  means  are  combinations  of 
plane  reflectors,  concave  reflectors,  double  convex  or  plano- 
convex lenses.  The  appendages  to  the  solar  camera  and 
to  the  solar  microscope  are  fac-similes  of  each  other  ;  but 
the  solar  microscope  existed  before  photography  had  been 
elicited  from  chaos ;  the  solar  camera,  therefore,  is  a  mere 
imitation  of  its  antecedent ;  the  patentees  of  the  latter  instru- 
ment, then,  can  make  no  claim  to  originality  of  design  ;  their 
only  claim  can  be  the  application  of  the  instrument  to  pho- 
tography. 

Solar  Microscope. 
The  appendages  to  the  solar  microscope,  that  is,  the  con- 
densing part  of  the  apparatus,  consist  in  the  first  place  of  a 
plane  mirror  in  the  form  of  a  rectangle,  whose  width  is  at 
least  equal  to  the  diameter  of  the  plano-convex  or  double 


258  PRINTING  OF  TRANSPARENT  POSITIVES 


convex  lens,  which  condenses  the  light  received  from  the 
mirror.  The  length  of  the  mirror  must  be  about  four  times 
its  width.  At  one  end  there  is  a  hinge-joint,  which  allows 
the  mirror  to  swing  on  the  same  like  a  door.  The  hinge  is 
fixed  to  a  circle  of  brass  or  other  metal,  which,  by  means  of 
a  dentated  periphery,  admits  of  a  circular  motion.  By  this 
contrivance  it  will  be  seen  that  the  mirror  has  two  motions 
at  right  angles  to  each  other ;  for  instance,  supposing  the 
back  of  the  mirror  faced  the  sun  at  noon,  and  were  perpen- 
dicular to  the  horizon,  then  one  of  the  motions  mentioned 
would  cause  the  mirror  to  incline  toward  the  sun,  until  finally 
it  would  be  flat  on  the  horizon.  The  other  motion  permits 
the  mirror  to  move  either  toward  the  East  or  the  West ;  so 
that,  as  it  now  stands,  if  moved  toward  the  West,  the  sil- 
vered surface  would  face  the  setting  sun.  By  combining 
these  two  motions  consentaneously,  the  mirror  can  always  be 
so  inclined  as  to  reflect  the  rays  of  the  sun  from  rising  to 
setting  into  the  axis  of  the  condenser.  The  two  motions  in 
question  are  effected  by  means  of  screws  and  pinion-wheels, 
etcetera. 

The  part  just  described  might  be  a  concave  mirror  admit- 
ting of  the  same  motions  ;  this  would  act  as  a  reflector  and 
condenser  at  the  same  time.  The  condenser  is  fixed  in  the 
brass  plate  which  is  attached  to  the  window-shutter,  and 
around  the  condenser  the  metallic  ring  moves,  to  which  the 
hinge  of  the  mirror  is  attached.  The  object  of  this  part  of 
the  apparatus  is,  by  refraction,  to  cause  the  large  bundle  of 
parallel  rays  that  impinge  upon  its  surface,  to  be  condensed 
from  a  cylindrical  into  a  conical  form,  so  that  at  a  given  dis- 
tance this  converging  and  condensed  light  will  arrive  at  its 
apex  or  focus. 

Now,  at  this  focus,  all  the  light  that  has  passed  through  the 
lens  will  be  concentrated  ;  and  at  a  variable  distance,  before 
it  arrives  at  this  focus,  it  will  cover  a  variable  space,  vary- 
ing from  a  point  or  zero  upward  to  an  amount  equal  to  the 
surface  of  the  lens. 

The  amount  of  condensation  will  be  the  ratio  between  the 
squares  of  the  distances  from  the  focal  point ;  thus,  suppose 
the  focal  distance  be  twelve  inches,  and  that  we  intercept 
the  cone  of  light  at  three  inches  from  the  focus  ;  then  by  di- 
viding the  square  of  twelve  by  the  square  of  three  we  obtain 
the  ratio,  which  is  sixteen,  and  this  indicates  that  the  light 
at  this  distance  is  sixteen  times  more  intense  than  it  was 
when  it  first  immerged  from  the  lens. 

The  object  of  the  refracting  lens,  therefore,  is  to  illumine 


BY  THE   DRY  PROCESS. 


259 


the  object  with  light.  This  is  the  primary  view  of  the  matter, 
but  it  does  more  than  this ;  each  ray  from  the  condenser  not 
only  illumines  each  point  on  the  transparent  object  upon 
which  it  impinges,  but  on  emergence  after  refraction  it  passes 
on  modified  by  the  medium  through  which  it  has  penetrated, 
and  carries,  so  to  say,  this  part  of  the  picture  with  it ;  the 
cone  of  modified  light  is  in  fact  the  picture  set  in  motion,  and 
so  directed  as  to  strike  the  surface  of  the  camera-lens  which 
is  next  to  it.  These  rays  are  convergent,  and  are  each  the 
axis  of  an  independent  cone  of  divergent  rays  from  each  illu- 
mined point  of  the  transparent  negative.  Some  photogra- 
phers maintain  that  the  axes  alone  (that  is,  the  rays  that  con- 
stitute the  cone  of  light  from  the  condenser)  are  available, 
and  that  the  divergent  rays  around  each  axis  are  of  no  avail. 
This,  however,  is  a  mistake,  and  is  equivalent  to  saying  that, 
if  an  opaque  object  were  illumined  by  a  condenser  or  reflec- 
tor, the  picture  could  be  taken  only  by  focussing  the  cone  or 
the  beam  of  reflected  light ;  .whereas  we  know  full  well  in 
copying  that  the  rays  that  enter  the  camera  through  the  lens, 
and  that  go  to  the  formation  of  the  picture,  can  not  be  any 
of  the  reflected  rays,  because  these  are  perpendicular  to  the 
surface  of  the  copy,  and  would  indicate  that  the  impingent 
rays  were  also  perpendicular,  which  is  an  impossibility,  ow- 
ing to  the  opacity  of  the  camera  and  its  tube,  which  occlude 
all  perpendicular  rays.  On  the  contrary,  each  illumined  point 
becomes  a  new  radiant,  from  which  proceeds  a  divergent  pen- 
cil of  rays,  of  which  many  around  the  axis  are  refracted  by 
the  lens  and  brought  to  a  focus  on  the  other  side. 

If  the  condensing  lens  be  achromatic,  the  light  will  be 
white  ;  if  not  achromatic,  it  will  produce  spectral  colors,  of 
which  some  are  useless  in  photography,  whilst  others  are 
exactly  those  which  are  needed.  Now  the  scientific  optician 
can  arrange  his  non-achromatic  condenser  in  such  a  manner, 
in  reference  to  the  lens  and  the  negative,  as  to  make  use  only 
of  the  violet  light,  or  the  actinic  part  of  the  spectrum,  for 
the  formation  of  the  picture.  The  focus  of  the  violet  or  ac- 
tinic light  is  shorter  than  that  of  the  luminous  or  yellow  part. 

The  next  appendage  to  the  solar  microscope  is  the  object- 
holder,  which  has  a  sliding  motion  to  or  from  the  condenser, 
in  the  neighborhood  of  the  focus,  by  which  means  the  object 
can  be  placed  in  a  condensed  part  of  the  cone  of  light,  which 
is  just  sufficient  to  cover  it  and  no  more,  a  contrivance  by 
which  light  is  economized. 

The  remaining  part  of  the  instrument  is  the  microscope 


260 


FEINTING  OF  TRANSPARENT  POSITIVES 


proper,  which  contains  the  corrected  objective  for  magnify- 
ing the  object. 

ISTow  the  above  description  is  precisely  the  same  as  that 
of  the  condensing  part  of  the  solar  camera.  With  such  an 
arrangement  of  mirrors  and  refractors,  the  camera  and  screen 
may  remain  fixed  during  the  whole  time  of  the  operation. 

Another  arrangement  for  concentrating  light  is  accom- 
plished by  means  of  reflectors  fixed  in  the  form  of  a  frustum 
of  a  pyramid.  But  in  the  application  of  this  contrivance 
the  camera  and  screens  must  all  move  together  on  a  univer- 
sal joint,  like  a  heliostat,  by  which  means  the  silvered  sur- 
faces of  the  reflectors  can  always  be  preserved  in  front  of 
the  sun,  so  as  to  catch  his  rays,  (as  described  in  a  pre- 
vious chapter  of  this  work.) 

The  mode  of  using  the  solar  microscope  and  the  solar  cam- 
era is  in  no  wise  different,  excepting  that  in  the  former  a 
transparent  object  is  substituted  in  the  holder  for  the  trans- 
parent collodion  negative  in  the  latter.  Each  is  placed  in 
the  cone  of  condensed  light,  in  order  to  be  brilliantly  illu- 
mined, and  in  such  a  position,  in  reference  to  the  objective 
or  photographic  lens,  as  to  bring  the  focus  of  the  actinic  rays 
immediately  on  the  optical  center  of  the  last  or  front  lens  of 
the  combination.  It  is  by  this  means  alone  that  the  best  en- 
larged picture  can  be  obtained. 

How  to  find  the  point  where  the  Lens  is  to  he  placed. 

It  appears  then  that  the  lens  may  not  be  placed  in  any  po- 
sition for  maximum  effect ;  the  true  position  depends  upon  the 
power  of  the  condenser,  in  combination  with  the  power  of 
the  posterior  lens  of  the  tube,  where  such  is  used.  There 
must  be  a  relative  connection  between  these  two  powers ; 
but  this  is  not  maintained  in  any  of  the  solar  cameras  in  the 
market,  from  the  fact  that  tubes  are  not  considered  as  parts  of 
the  solar  camera  ;  operators  are  consequently  left  to  apply 
whatever  combination  they  may  have  on  hand ;  we  must 
therefore  avail  ourselves  of  what  is  next  best,  and  fix  the 
combination  where  the  maximum  effect  can  be  obtained  witli 
given  materials. 

Knowing  the  length  of  the  principal  focus  of  the  conden- 
ser and  its  diameter,  as  well  as  that  of  the  compound  lens 
from  the  posterior  lens,  the  mathematician  can  easily  calcu- 
late how  much  the  former  focus  will  be  shortened  by  the  in- 
terposition of  the  tube.  Supposing,  for  instance,  the  diame- 
ter of  the  condenser  be  eight  inches,  and  its  focal  length  be 
twelve  inches,  then  the  angle  which  the  side  of  the  cone  of 


BY  THE  DRY  PROCESS. 


261 


condensed  light  makes  with  the  diameter  will  be  71°  '.23 
Moreover,  let  the  diameter  of  the  posterior  lens  be  two 
inches,  and  the  focal  length  from  the  back  lens  two  inches, 
then  the  angle  formed  between  the  side  of  its  cone  and. 
the  diameter  will  be  63°  45'.  That  is,  if  the  rays  entered 
the  combination  parallel,  they  would  form  a  cone,  of  which 
the  outside  ray  would  have  this  angle  with  the  diameter  of 
the  back  lens.  But,  being  interposed  in  the  cone  of  condens- 
ed light,  of  which  the  rays  are  convergent,  the  tendency  of 
the  combination  is  to  shorten  the  focal  length,  by  reducing 
the  angle  63°  45'  to  56°  00',  the  difference  between  these 
t  wo  angles  being  the  same  difference  that  exists  between  71° 
32' and  63°  45'.  As  the  angle  diminishes,  so  will  the  focal 
length  of  the  cone  of  condensed  light  be  diminished,  and  in 
the  present  instance  to  the  amount  of  half  an  inch. 

Besides  this,  we  have  to  reduce  this  distance  still  more,  in 
order  to  find  the  actinic  focus,  which  the  mathematical  opti- 
cian can  easily  find. 

But  the  generality  of  photographers  are  not  supposed  to 
be  in  a  condition  to  deduce  the  requisite  corrections  in  this 
way ;  we  must  therefore  show  by  practical  means  how  we 
can  approximate  to  the  same  results. 

Ascertain  the  focal  length  of  the  condenser  by  finding  the 
distance  of  its  burning  point  from  the  glass ;  then,  when  the 
tube  is  screwed  out  to  the  extent  of  its  play,  measure  the 
distance  from  the  face-plate,  in  which  the  tube  is  fastened, 
to  the  front  lens  ;  subtract  this  distance  from  the  focal  length 
of  the  condenser,  the  difference  will  give  the  distance  of  the 
condenser  to  the  outside  of  the  camera  nearly,  or  to  the  part 
upon  which  the  face-plate  of  the  tube  is  to  be  screwed.  More 
accurately  the  same  result  can  be  obtained  by  interposing 
the  tube  in  the  condensed  light,  and  by  moving  it  backward 
and  forward,  until  the  focal  or  burning  point  is  just  on  the 
outside  of  the  front  lens;  let  an  assistant  measure  this  dis- 
tance from  the  outside  of  the  camera,  and  at  this  distance 
fix  the  tube  permanently.  Whilst  doing  this  the  greatest 
care  is  required  to  make  the  axis  of  the  condenser  coincide 
with  the  axis  of  the  tube. 

This  is  the  first  rude  adjustment.  The  second  adjustment 
consists  in  bringing  the  actinic  focus  so  as  to  coincide  with 
the  optic  center  of  the  front  lens.  Screw  back  the  sliding 
part  of  the  tube  and  turn  on  the  sun  ;  the  luminous  focus  will 
be  quite  visible  in  the  dark  space  behind  the  camera.  Now 
insert  a  piece  of  deep  violet-colored  glass  between  the  con- 
denser and  the  objective,  so  as  to  intercept  all  the  colors  of 


262 


PRINTING  OF  TRANSPARENT  POSITIVES 


the  luminous  cone,  excepting  the  violet,  and  ascertain  where 
the  violet  cone  comes  to  a  focus  ;  screw  the  tube  out  until 
this  focus  is  just  in  front  of  the  anterior  glass  ;  then,  knowing 
the  thickness  of  the  front  lens,  advance  the  tube  until  the 
blue  focus  is  in  the  middle  of  the  front  lens,  and  let  this  be 
the  final  and  permanent  adjustment  of  the  tube  in  reference 
to  the  condenser.  Mark  this  position  by  a  line  on  the  brass 
work,  in  order  that  the  tube  can  be  adjusted  at  a  moment's 
notice  when  required  to  be  used. 

The  negative-holder  is  movable  by  means  of  a  screw,  so 
that  it  can  be  brought  into  focus  upon  any  screen  on  the 
other  side  of  the  tube.  Whenever  this  operation  of  focus- 
sing is  to  be  performed,  insert  the  violet-colored  glass,  so  as 
to  focus  in  reference  to  actinism,  and  not  to  luminosity.  By 
this  means  the  luminous  picture  on  the  screen  (that  is,  when 
the  violet-colored  glass  is  removed)  may  not  be  quite  sharp, 
but  the  printed  picture  on  the  paper  will  be  sharp  and  beau- 
tifully defined.  The  same  mode  of  proceeding  may  be  fol- 
lowed with  the  ordinary  camera,  where  there  is  any  doubt 
of  the  correction  of  the  tube  for  actinism.  Place  in  front  of 
the  tube  a  piece  of  violet-colored  glass  every  time  you  focus. 

Macrophotography ,  or  the  Art  of  Taking  Enlarged 
Photographs. 

The  Negative  for  Enlargement, 
The  size  of  the  negative  will  have  to  depend  on  the  diam- 
eter of  the  condenser ;  if  this  be  nine  inches,  a  one-sixth  plate 
will  be  large  enough,  the  object  being  to  get  the  negative  as 
near  the  apex  of  the  cone  of  concentrated  light  as  possible, 
and  in  such  a  position  as  to  be  totally  covered  by  the  cone. 

TJie  Quality  of  the  Negative. 
The  negative  suitable  for  the  solar  camera  must  be  very 
bright,  well  defined  and  quite  clear.  The  glass  must  be  thin, 
perfectly  flat,  or  in  the  same  plane  and  homogeneous.  The 
negative  effect  need  not,  in  fact,  must  not  be  carried  on  to 
the  same  extent  as  for  positive  printing ;  it  is  but  a  trifle  in 
advance  of  the  ambrotype  ;  if  there  should  happen  to  be  the 
slightest  quantity  of  fogging,  that  is,  reduction  on  the  trans- 
parent parts,  it  will  be  necessary  either  to  take  another  ne- 
gative or  to  clear  off  the  fogginess.  This  is  effected  by  flow- 
ing the  plate  with  a  dilute  solution  of  iodine  in  iodide  of 
potassium,  until  the  picture  turns  slightly  cream-colored; 
the  plate  is  then  washed  and  flowed  with  a  solution  of  cyan- 
ide of  potassium,  which  dissolves  the  newly  formed  iodide 


THE  DRY  PROCESS.  263 

of  silver  and  thus  clarifies  the  picture.  As  soon  as  the  latter 
is  satisfactory,  as  to  brightness,  cleanness,  and  fine  definition, 
wash  and  dry  the  plate,  but  apply  no  varnish. 

As  soon  as  the  negative  is  in  its  place,  and  accurately  fo- 
cussed  actinically,  fix  the  prepared  paper  on  the  screen  in  its 
place.  In  order  to  preserve  the  paper  perfectly  flat  and 
smooth,  sponge  the  back  with  a  wet  sponge,  and  after  it  has 
thoroughly  expanded,  and  lies  uniformly,  and  without  undu- 
lations, go  round  the  edge  to  the  amount  of  half  an  inch  on 
the  same  surface  which  has  been  sponged  with  a  thick  solu- 
tion of  gum-arabic  ;  attach  the  paper  so  prepared  to  an  even 
plate  of  glass  or  drawing-board,  of  somewhat  smaller  dimen- 
sions than  the  paper,  and  allow  it  to  dry.  When  dry,  all 
the  corrugations  and  undulations  will  have  disappeared  ;  the 
paper  will  be  smooth  and  flat,  and  ready  to  receive  the  image, 
supposing  naturally  it  has  already  been  sensitized  in  the  sil- 
ver bath.  If  this  operation  has  been  neglected  or  omitted, 
the  silver  solution  can  be  very  expeditiously  poured  upon 
the  surface  and  spread  with  a  pad  or  tuft  of  cotton  wool, 
until  the  film  is  uniform.  The  excess  of  silver  is  then  re- 
moved, and  the  plate  is  reared  on  one  corner  over  a  wine- 
glass to  receive  the  drippings. 

When  dry  it  is  placed  in  the  focus  of  the  negative,  and 
the  sun  is  turned  on.  By  means  of  the  two  screws  on  the 
solar  camera,  the  sun's  light  is  maintained  in  its  position 
during  the  whole  operation.  Printing  on  albumenized  pa- 
per by  the  solar  camera  is  a  tedious  operation,  requiring 
sometimes  several  hours  before  it  is  complete,  and  some- 
times even  a  day  or  two  by  reason  of  the  cloudiness  of  the 
sky.  Where  this  sort  of  printing  is  practicable,  as  is  the  case 
generally  in  our  own  country,  the  results  are  the  best. 
Printing  by  development,  however,  is  more  reliable,  because 
it  is  altogether  independent  of  the  condition  of  the  sky,  wheth- 
er cloudy  or  cloudless. 

Several  processes  for  printing  by  development  will  be 
found  in  the  chapter  in  which  this  subject  has  been  discuss- 
ed. I  will  insert  another  in  this  place,  from  its  applicability 
and  reliability.  It  is  the  process  of  Blanquart-Evrard, 
whose  prints  have  been  so  much  admired. 

JBromo-iodizing  Bath  for  Paper. 


Water,   12  ounces. 

Gelatine,   1  drachm. 

Iodide  of  potassium,   1  drachm. 

Bromide  of  potassium,    15  grains. 


264 


POINTING  OF  TRANSPAKENT  POSITIVES 


Immerse  the  papers  in  this  bath,  as  many  at  a  time  as  it 
will  contain,  and  keep  them  there  for  two  or  three  hours. 
The  bath  can  be  used  over  and  over  again  until  exhausted. 
The  papers  are  then  taken  out  and  nung  up  to  dry.  As 
soon  as  they  are  dry  they  may  be  preserved  in  a  portfolio 
for  use. 

Previous  to  being  sensitized  they  are  exposed  for  a  quar- 
ter of  an  hour  to  the  vapor  of  hydrochloric  acid.  This  op- 
eration is  easily  effected  by  fixing  the  paper  along  the  sides 
and  under  the  lid  of  a  large  nearly  air-tight  box,  by  means 
of  varnished  pins.  At  the  bottom  of  the  box  place  a  saucer 
containing  a  handful  of  salt,  an  ounce  or  two  of  sulphuric 
acid,  and  half  as  much  boiling  water.  Vapors  of  hydrochlor- 
ic acid  will  be  generated  in  abundance,  and  will  thus  saturate 
the  paper. 

Sensitizing  Bath. 

Nitrate  of  silver,  1  ounce. 

Distilled  water,  14  ounces. 

Nitric  acid  to  give  it  an  acid  reaction. 

Let  the  paper  float  in  this  bath  for  ten  minutes.  By  de- 
composition they  will  now  contain  the  iodide,  bromide,  and 
chloride  of  silver.  After  sensitization  they  are  allowed  to 
drain,  and  then  dried  either  by  pressure  between  folds  of 
bibulous  paper  or  by  suspension  in  the  dark-room. 

The  exposure  required  will  vary  from  a  couple  of  seconds 
to  half  a  minute  beneath  a  negative,  and  longer  than  this  on 
the  screen  of  the  solar  camera.  When  the  image  is  just 
visible,  the  printing  has  been  carried  on  long  enough. 

Development. 

The  picture  is  brought  out  by  immersing  it  in  the  ordina- 
ry gallic  acid  bath,  at  a  temperature  of  80  degrees,  and  by 
keeping  it  there  for  a  quarter  of  an  hour  or  more  as  cir- 
cumstances require.  The  bath  must  be  large  enough  for 
many  pictures  at  a  time ;  these  are  kept  in  motion  all  the 
while.  They  assume  a  disagreeable  color,  and  become  cov- 
ered with  spots  which  are  removed  by  the  operations  after- 
ward. As  soon  as  the  depth  of  shade  is  sufficiently  intense, 
the  prints  are  taken  out,  laid  one  by  one  on  a  glass  plate,  and 
sponged  on  both  sides  and  then  immersed  in  a  bath  of  hypo- 
sulphite of  soda  for  five  minutes,  in  which  they  are  toned. 

Hyposulphite  of  soda,  1  ounce. 

Bain-water,  20  ounces. 

After  this  they  are  removed  direct  into  a  second  bath  of 
hyposulphite  of  soda  of  the  same  strength,  and  are  allowed 


BY  THE  DRY  PROCESS. 


265 


to  remain  for  twenty  minutes,  in  which  they  are  completely 
fixed. 

The  prints  are  then  carefully  washed  in  several  waters 
and  finally  immersed  in  a  bath  of  dilute  hydrochloric  acid, 
which  removes  a  yellow  deposit  and  the  spots  above  men- 
tioned. A  second  washing  completes  the  operation,  with 
the  exception  of  drying  and  exposing  to  the  action  of  light 
for  several  weeks,  which  improves  the  reddish  tone  by  chang- 
ing it  gradually  into  purple. 

These  prints  will  keep  for  an  indefinite  time,  although 
toned  with  sulphur. 

Microphotography,  or  the  Art  of  talcing  Diminished  Copies 
of  Photographs,  or  Photographs  of  Microscopic  Objects. 

Diminished  Photographs. — It  is  a  much  easier  operation 
to  diminish  the  size  of  a  photograph  or  object  by  photo- 
graphic means  than  to  amplify  one  ;  and  the  result  in  general 
is  more  satisfactory,  because  all  the  errors  of  the  original 
are  diminished  in  the  same  ratio  as  the  whole  picture  is 
diminished.  In  order  to  take  portraits  so  invisibly  small 
as  not  to  be  seen  without  the  aid  of  a  magnifier,  we  require 
a  small  camera  specially  arranged  for  the  purpose.  Such 
cameras,  furnished  with  the  necessary  objective,  are  manu- 
factured by  JBertsch  in  Paris.  The  tube  requires  no  focus- 
sing ;  the  only  condition  to  be  observed  is  to  place  the  pho- 
tograph, object,  or  print  to  be  copied  at  or  beyond  a  given 
distance.  All  lenses  have  this  property  of  requiring  but  one 
adjustment,  which  is  permanent  when  once  found,  for  objects 
beyond  a  given  distance,  which  varies  directly  as  the  focal 
distance  or  power  of  the  lens.  Lenses  for  the  diminutive 
pictures  in  question  are  in  focus  for  all  distances  beyond 
three  feet  or  so.  Objectives,  such  as  are  sold  for  microscopic 
purposes,  whose  focal  distances  are  one  inch,  half  an  inch,  or 
a  quarter  of  an  inch,  may  easily  be  arranged  in  a  very  small 
camera  to  take  these  diminutive  portraits.  But  very  little 
ingenuity  will  suffice  to  make  such  a  camera  out  of  a  small 
telescope,  where  one  tube  slides  into  another.  In  the  end 
of  the  inner  tube  the  objective  is  fixed;  in  the  end  of  the 
outer,  the  ground  glass  and  the  plate-holder.  This  com- 
pound tube  is  fixed  permanently  upon  a  solid  support  six 
inches  high,  on  a  piece  of  board  four  or  five  feet  in  length 
or  even  more.  On  the  opposite  end  of  the  board  a  plane  is 
erected  at  right  angles  to  the  former  and  also  to  the  axis  of 
the  camera.  Find  the  point  on  this  vertical  board  where 
the  axis  cuts  the  same,  and  mark  it  as  the  center  of  the  pic- 
12 


266 


PRINTING  OF  TRANSPARENT  POSITIVES 


ture  to  be  copied.  The  picture  is  fixed  upon  this  plane  by 
means  of  tacks  or  pins  in  an  inverted  position  and  so  that 
its  center  coincides  as  near  as  possible  with  the  mark  just 
made. 

The  next  proceeding  is  to  focus  the  lens.  Take  the  long 
board  and  place  it  so  as  to  receive  the  sun's  rays  upon  the 
picture.  ~Now  move  the  inner  tube  of  the  camera  in  and 
out  until  the  image  is  seen  on  the  ground  glass  by  means  of 
a  powerful  magnifier.  Focus  with  the  greatest  sharpness. 
This  operation  is  very  refined  and  requires  a  great  deal  of 
patience.  When  the  utmost  definition  is  thus  obtained, 
place  before  the  opening  of  the  tube  a  piece  of  very  thin 
violet-colored  glass  and  see  if  the  image  is  still  sharp  ;  if  it 
be,  fix  the  two  tubes  permanently  so  that  their  relative  posi- 
tion can  not  be  changed.  In  future  this  operation  of  focus- 
sing is  no  longer  required.  If,  however,  the  picture  is  not 
sharp  when  the  violet-colored  glass  is  interposed,  focus  until 
you  get  perfect  definition,  and  then  fix  as  just  directed. 

The  glass  to  receive  the  picture  is  thin  and  homogeneous; 
it  is  flowed  also  with  a  very  thin  collodion  and  sensitized  as 
usual.  All  the  operations  are  precisely  the  same  as  those 
already  described  in  the  preparation  of  the  ambrotype.  Of 
course  a  pair  of  spectacles  of  very  high  magnifying  power  is 
required  while  developing,  fixing,  and  mounting.  With  a 
pair  of  pliers  or  forceps  the  small  piece  of  glass  can  be  broken 
down  so  as  to  fit  into  the  ring,  etc.,  which  is  to  receive  the 
picture. 

The  objectives  manufactured  by  Grunow  in  New-York  for 
microscropes  have  succeeded  quite  well  with  me  in  the  pro- 
duction of  almost  invisible  pictures  ;  and  I  have  no  doubt  he 
will  be  able  to  fit  up  a  microscopic  camera  for  such  as  require 
one  from  the  indications  here  given.  Such,  a  camera,  requir- 
ing great  refinement  of  workmanship,  will  of  course  be  more 
likely  to  be  better  made  by  those  who  are  accustomed  to 
the  refined  adjustments  of  a  microscope  than  by  the  photo- 
grapher himself.  The  objectives  of  Grunow  are  not  only 
unexceptionable,  but  are  endowed  with  qualities  superior  to 
those  in  many  of  foreign  origin. 

Microscopic  Objects.  —  The  objectives  just  alluded  to 
are  very  well  suited  for  taking  enlarged  photographs  of 
microscopic  objects,  such  as  the  porous  structure  of  wood, 
the  siliceous  deposit  in  guano,  blood  corpuscles,  starch 
granules,  itch  insects,  etc.  Such  an  objective  is  fixed 
to  an  ordinary  bellows  camera,  so  arranged  on  a  sliding 
platform  that  the  axis  of  the  objective   coincides  with 


BY  THE  DRY  PROCESS. 


267 


the  axis  of  the  cone  of  concentrated  light  from  the 
condenser  of  the  solar  microscope.  The  latter  instrument 
has  a  special  opening  between  the  condenser  and  the  object- 
ive to  receive  the  transparent  object  whose  photograph  is  to 
be  taken  of  an  enlarged  size.  If  the  objective  is  not  quite 
achromatic,  insert  a  piece  of  thin  violet-colored  glass  over 
the  object  while  focussing,  and  fix  the  objective  so  that  the 
violet  cone  of  light  terminates  in  the  optic  center  of  the 
objective  as  before  described.  Focus  by  means  of  a  pair  of 
very  powerful  spectacles  or  a  compound  microscope.  In  the 
first  place  make  the  camera  firm  on  the  platform,  when  the 
objective  is  once  in  its  place  ;  then  draw  out  the  ground  glass 
nearly  as  far  as  it  will  go,  and  afterward  move  the  micro- 
scopic object  nearer  or  farther  off,  as  the  case  may  be,  by 
means  of  the  thumb-screw,  until  the  picture  is  visible  on  the 
ground  glass  ;  finally  focus  with  accuracy  so  as  to  get  perfect 
sharpness.  The  violet-colored  glass  may  now  be  withdrawn. 
The  prepared  collodion  plate  is  inserted  in  the  place  of  the 
ground  glass  ;  the  slide  is  drawn  out,  and  the  sun's  light 
turned  on  for  a  fraction  of  a  second.  It  is  in  many  instan- 
ces an  advantage  to  keep  the  violet-colored  glass  in  its  place, 
because  it  moderates  the  light ;  and  the  result  is  even  better 
with  it  than  without  it. 

Finish  the  plate  for  a  positive  or  negative  according  to 
rules  already  prescribed  in  ordinary  photography. 


CHAPTER  XXXIX. 


THE  DAGUERREOTYPE. 

A  photograph  on  a  silver  or  silvered  plate  is  superior  in 
definition  and  beauty  to  all  other  photographs  taken  on  other 
materials.  It  has,  however,  its  disadvantages  ;  amongst 
these  may  be  reckoned  the  lateral  inversion  of  the  picture, 
the  inability  of  regarding,  the  image  at  all  angles  of  reflec- 
tion, and  of  producing  reproductions  of  the  original  by 
some  quick  printing  process. 

The  Daguerreotype  process  is  divided  into  six  different 
operations. 

First  Operation,  or  the  Cleaning  and  Polishing  of  the 
Silvered  Plates. 

Copper  plates  can  be  purchased  already  silvered  with  a 
pure  frosted  silver  surface,  of  the  proper  size  and  ready  for 
the  polishing.  In  the  first  place,  with  a  pair  of  shears,  clip 
off  the  four  corners  of  the  plate,  about  a  quarter  of  an  inch 
from  the  apex  of  each  angle  ;  next  with  the  machine  for  this 
purpose  make  a  ledge  all  round  the  plate  of  one  tenth  of  an 
inch  in  width  from  the  silver  side  toward  the  copper  side, 
so  as  to  form  a  groove  such  as  the  tinman  makes  when 
grooving  two  edges  of  tin  together.  The  plate  is  then  fixed 
on  a  patent  plate-holder,  which  in  its  turn  is  next  screwed 
tight  in  the  plate-vice.  In  this  condition  the  silvered  surface 
can  easily  be  cleaned.  This  is  effected  by  means  of  rotten 
stone,  alcohol  and  Canton  flannel,  which  are  used  in  the  same 
manner  exactly  as  in  the  cleaning  of  glass  plates.  As  soon 
as  the  plate  is  perfectly  smooth  and  free  from  scratches,  it  is 
polished  with  what  is  called  the  buff,  which  consists  of  a 
piece  of  wood,  about  fifteen  or  eighteen  inches  long,  four 
or  five  wide,  and  about  three  quarters  of  an  inch  thick ; 
this  piece  is  slightly  curved  longitudinally  like  the  rocker 
of  a  chair,  though  to  a  less  extent.  It  is  well  padded 
on  the  convex  surface  and  finally  covered  with  chamois 
leather.    On  the  surface  scatter  a  small  quantity  of  jewel- 


THE  DAGUERREOTYPE. 


269 


er's  rouge,  (sesquioxide  of  iron,)  and  then  holding  the  buff* 
by  either  end  in  the  right  and  left  hand  move  it  backward 
and  forward  over  the  smooth  silver  plate,  first  in  one  direc- 
tion and  then  at  right  angles  to  it,  until  the  surface  has  a 
very  uniform  rich  polish,  devoid  of  lines.  The  plate  is  then 
ready  for  being  sensitized.  The  buffing  is  more  easily  and  uni- 
formly executed  on  what  is  denominated  the  buffing- wheel. 

Second  Operation,  or  the  Sensitizing  of  the  Silver  Plate. 

For  this  purpose  two  coating-boxes  are  required,  one  con- 
taining the  vapor  of  iodine,  and  the  other  that  of  bromine. 
They  are  so  arranged  as  to  allow  the  introduction  of  the 
polished  plate  without  any  loss  of  vapor.  These  boxes  must 
be  kept  at  a  warm  temperature  so  as  to  evolve  the  vapors 
from  the  materials ;  in  winter  artificial  heat  is  used.  One 
coating-box  contains  at  the  bottom  first  a  piece  of  Canton 
flannel,  and  then  about  half  an  ounce  or  more  of  iodine  in 
crystals ;  the  other  contains  a  mixture  of  hydrated  lime  and 
bromine,  well  pulverized  and  mixed.  The  operation  is  per- 
formed in  the  dark-room  near  the  orange-colored  pane  of 
glass.  The  polished  plate  is  first  inserted  in  the  holder  of 
the  iodine  coating-box,  and  the  lid  is  then  closed.  The  sur- 
face, if  examined  closely,  assumes  various  shades  of  color, 
beginning  with  light  yellow,  then  deep  yellow,  reddish,  cop- 
per-red, violet,  blue,  and  green.  As  soon  as  the  plate  passes 
from  the  yellow  to  the  red,  it  is  placed  over  the  bromine 
vapor,  and  kept  there  until  the  reddish  color  changes  into  a 
violet  or  steel  color  ;  it  is  then  put  back  again  over  the  iodine 
for  one  third  of  the  time  of  the  first  exposure.  By  this  means 
the  film  receives  a  very  high  degree  of  sensibility.  The  times 
of  these  three  exposures,  as  soon  as  determined  by  practice, 
are  counted  in  seconds.  A  more  sensitive  film  may  be  ob- 
tained by  iodizing  simply  to  the  light  yellow,  by  bromizing 
to  the  dark  yellow,  and  then  again  over  the  iodine  for  one 
third  of  the  first  exposure.  This  film,  however,  is  very  thin 
and  not  suitable  for  portraits,  although  well  adapted  for  views. 
The  plate  is  now  ready  for  the 

TJiird  Operation,  or  the  Exposure  to  IAght. 

It  has  been  observed  that  the  sensitized  plates  are  more 
sensitive  to  the  actinic  impression  if  not  exposed  for  a  quar- 
ter of  an  hour  after  sensitization ;  in  general,  however,  the 
plate  is  transferred  directly  from  this  operation  to  the  plate- 
holder  of  the  camera,  and  exposed  right  away.  The  time  of 


270 


THE  DAGUEEKEOTYPE. 


exposure  is  very  short ;  it  is  naturally  various,  as  in  all  other 
and  similar  cases  depending  upon  the  brilliancy  of  the  light, 
the  season  of  the  year,  the  time  of  the  day,  and  other  minor 
circumstances.  A  few  seconds,  even  in  the  room,  are  mostly 
quite  sufficient.  The  exact  number  is  easily  learned  from  the 
conditions  of  the  case  ;  and  then  the  exposure  afterward  can 
be  regulated  by  counting.  The  plate  is  next  withdrawn  from 
the  plate-holder  in  the  dark-room  ;  it  contains  no  visible 
image  ;  this  is  made  to  appear  by  proceeding  to  the 

Fourth  Operation,  or  Developing  by  the  Vapor  of  Mercury. 

A  cast-iron  box  is  prepared  for  this  purpose,  capable  of 
being  well  closed  after  the  plate  is  introduced.  It  contains 
mercury  at  the  bottom,  which  is  kept  at  the  temperature  of 
from  120°  to  150°  Fahrenheit,  by  means  of  a  lamp  with  a 
small  flame  capable  of  graduation,  and  a  thermometer  attach- 
ed to  the  box  with  the  bulb  in  the  mercury.  A  couple  of 
ounces  of  mercury  will  be  sufficient  at  once  for  ordinary 
portraiture.  In  two  or  three  minutes  the  development  will 
be  complete.  At  intervals  the  plate  may  be  examined  to  see 
the  progress  of  development ;  but  this  examination  must  be 
made  with  great  care,  for  the  film  is  easily  fogged  by  expos- 
ure to  diffused  light.  If  the  time  of  exposure  has  been  too 
long,  the  whole  image  will  be  fogged  and  indistinct ;  where- 
as if  it  has  been  too  short,  the  high  lights  alone  will  be  de- 
veloped, Avhile  the  rest  will  undergo  no  change  whatever. 
Supposing  the  picture  to  possess  the  proper  gradation  of 
light  and  shade,  it  is  then  ready  for  the 

Fifth  Operation,  or  the  Fixing  of  the  Developed  Image. 
The  film  is  still  very  sensitive,  and  the  picture  in  a  few 
minutes  would  be  irremediably  spoiled,  unless  the  sensitive 
character  of  the  film  be  annihilated.  This  is  effected  by 
plunging  the  plate  immediately  into  the  fixing  solution, 
which  must  be  preserved  in  a  very  clean  condition  by  con- 
tinual filtration  after  each  operation.  The  fixing  solution 
consists  of: 

Hyposulphite  of  soda,  2  drachms. 

Distilled  or  rain-water,  2£  ounces. 

Agitate  the  plate  in  this  solution  for  a  few  seconds,  until 
the  iodizing  is  entirely  removed,  and  then  wash  the  plate  in 
distilled  water.  In  all  operations  of  washing  and  fixing,  use 
only  filtered  materials,  for  small  particles  of  dust  are  very 
visible  on  the  dried  plates  ;  use,  especially,  very  pure  water, 
because  ordinary  water  contains  salts,  which  are  left  as  a 


THE  DAGUERREOTYPE. 


271 


deposit  on  the  plates  when  dried.  After  the  fixed  plate  is 
well  washed  proceed  to  the  final  or 

Sixth  Operation,  or  the  Toning  with  Gold. 
In  the  first  place  make  a  ledge  round  the  plate  in  the  oppo- 
site direction,  so  as  to  form  a  miniature  dish  with  the  picture 
at  the  bottom ;  or  cut  off  the  former  ledges  entirely,  and 
holding  the  plate  by  one  of  its  corners  with  a  pair  of  pliers, 
pour  upon  the  surface  of  the  picture,  held  horizontally,  as 
much  of  the  following  gold  solution  as  it  will  hold  without 
flowing  over  the  edges : 

Toning  Solution. 

No  1  \  Chloride  of  gold,  1  grain. 

'  (  Distilled  water,  1  ounce. 

No  2  \  Hyposulphite  of  soda,  4  grains. 

*  (  Distilled  water,  1  ounce. 

Dissolve  and  pour  the  gold  solution  into  the  hyposulphite 
of  soda,  and  mix  well  together.  Next  light  a  spirit-lamp 
with  a  large  wick,  and  holding  the  pliers  and  plate  in  the 
left  hand,  play  beneath  the  plate  containing  the  toning  solu- 
tion with  the  flame  of  the  lamp  held  in  the  right  hand.  Do 
not  allow  the  flame  to  play  upon  the  same  spot ;  move  it 
about,  bubbles  will  soon  begin  to  arise,  and  the  picture  will 
soon  begin  to  assume  a  much  more  agreeable  tone.  Take 
care  to  have  an  excess  of  gold  solution  all  the  time  upon  the 
plate,  otherwise,  if  it  fails  on  a  certain  part  during  the  oper- 
ation of  gilding,  a  stain  will  be  produced  that  can  not  be 
removed  by  any  subsequent  treatment.  Use  also  a  large 
flame,  to  produce  rapid  action  ;  prolonged  action  fogs  the 
picture.  When  the  tone  of  the  picture  is  satisfactory,  im- 
merse the  plate  at  once  in  a  basin  of  water,  and  wash  well 
at  the  top  ;  afterward  pour  over  the  plate  two  or  three 
times,  distilled  water,  and  then  dry  the  plate ;  beginning  at 
the  upper  edge  with  the  application  of  the  flame  of  the 
lamp,  proceed  downward,  as  the  film  dries,  blowing  off  the 
excess  of  water  as  you  proceed,  or  absorbing  it  with  a 
sponge  from  the  pendent  edge  and  corners,  until  the  whole 
surface  is  dry. 

Daguerreotypes  may  be  touched  up  with  color  like  any 
other  photographs,  where  desired.  It  must  be  confessed, 
however,  that  a  well-toned  daguerreotype  picture  looks  best 
unadorned  with  either  color  or  tinsel. 


CHAPTER  XL. 


PRINTING   WITHOUT   THE    SALTS    OP  SILVER. 

These  processes  comprehend  several  operations  with  the 
persalts  of  iron,  chromium,  the  salts  of  uranium,  and  the  car- 
bon process.  They  are  very  interesting,  but  have  not  as  yet 
been  applied  to  any  useful  purpose.  The  carbon  process  has 
not  arrived  at  that  degree  of  perfection  which  is  expected 
in  such  operations.*  This  expression  of  its  merits  is  limited 
to  direct  printing  on  paper  by  carbon  or  other  colored  media 
in  connection  with  chrome  salts,  etc.  Photo-lithography  and 
its  congeners,  that  require  the  application  of  carbonaceous 
ink,  are  properly  classified  as  photo-engraving,  and  will  be 
treated  as  such. 

Process  with  the  Salts  of  Iron. 

Sir  John  Herschel  discovered,  several  years  ago,  that  cer- 
tain of  the  persalts  of  iron,  when  exposed  to  light  in  connec- 
tion with  organic  matter,  undergo  decomposition,  and  are 
reduced  to  the  state  of  proto-salts and  we  are  indebted  to 
Poitevin  for  numerous  interesting  developments  in  this  de- 
partment. For  instance,  the  perchloride,  so  exposed,  becomes 
reduced  to  the  proto-chloride,  or,  as  Van  Monckhoven  more 
appropriately  remarks,  to  the  state  of  oxy-chloride.  For 
this  purpose  the  sesquichloride  must  be  quite  neutral.  The 
ammonio-tartrate,  potassa-tartrate,  and  the  ammonio-citrate 
of  iron  are  much  more  sensitive  to  light  than  the  sesqui- 
chloride, and  the  latter  salt  the  most  of  all. 

The  image  formed  by  means  of  these  salts  is  much  fainter 
than  that  with  the  chloride  of  silver ;  but  it  can  be  inten- 
sified by  the  application  of  other  metallic  salts.  The  mode 
of  operation  consists  in  floating  the  paper  on  the  solutions  in 
question,  in  the  dark-room,  in  allowing  them  to  dry  and  then 
exposing  them  afterward  beneath  a  negative,  as  usual,  with 
paper  prepared  with  chloride  of  silver. 

*  Pouncy's  New  Carbon  Process  seems  to  give  great  promise  of  being 
usefully  applied. 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


273 


Cyanotype. — Float  on  a  solution  of  the  sesquichloride  of 
iron,  dry  and  expose ;  afterward  wash  the  prints,  and  then 
immerse  them  in  a  bath  of  ferridcyanide  of  potassium.  The 
picture  will  appear  of  a  blue  color  in  all  those  places  where 
the  sun  has  acted.  Ferridcyanide  of  potassium  has  no  action 
upon  the  persalts  of  iron ;  on  the  protosalts,  however,  it 
produces  prussian  blue. 

Crysotype. — If  the  papers  containing  the  faint  image,  pro- 
duced on  the  ammonio-citrate  of  iron,  be  floated  on  a  bath 
of  a  dilute  and  neutral  solution  of  chloride  of  gold,  the  image 
assumes  a  purple  tone,  which  becomes  gradually  darker  the 
longer  it  is  exposed  to  the  solution. 

Solutions  of  the  other  metals,  such  as  those  of  silver,  mer- 
cury, and  platinum,  also  produce  images  which  aiie  of  a  gray- 
ish color.  Bichromate  of  potash  yields  a  picture  by  a  similar 
decomposition. 

Process  with  the  Salts  of  Uranium. 

The  discovery  of  this  process  owes  its  origin  to  Niepce  de 
St.  Victor  and  to  Burnett.  The  nitrate  of  the  sesquioxide 
of  uranium  undergoes  in  connection  with  organic  matter, 
when  exposed  to  the  sun,  a  decomposition  analogous  to  that 
of  the  sesquichloride  of  iron. 

The  paper,  without  having  undergone  any  preceding 
preparation,  excepting  that  of  having  been  excluded  from 
the  light  for  several  days,  is  floated  on  a  bath  of  the  nitrate 
of  uranium,  as  follows  : 

Distilled  water,  10  drachms. 

Nitrate  of  uranium,  2  drachms. 

The  paper  is  left  on  the  bath  for  lour  or  five  minutes  ;  it  is 
then  removed,  hung  up  and  dried  in  the  dark-room.  So  pre- 
pared, it  can  be  kept  for  a  considerable  time. 

The  exposure  beneath  a  negative  varies  from  one  minute 
to  several  minutes  in  the  rays  of  the  sun,  and  from  a  quarter 
of  an  hour  to  an  hour  in  diffused  light.  The  image,  which 
is  thus  produced,  is  not  very  distinct,  but  comes  out  in  strong 
contrast  when  developed  by  one  of  the  following  developers : 

Nitrate  of  Silver  Developer. 

Distilled  or  rain-water,  2  drachms. 

Nitrate  of  silver,   7  grains. 

Acetic  acid,  a  mere  trace. 

The  development  is  very  rapid  in  this  solution ;  in  about 
half  a  minute  it  is  complete.    As  soon  as  the  picture  appears 
in  perfect  contrast,  the  print  is  taken  out  and  fixed  by  im- 
mersion in  water,  in  which  it  is  thoroughly  washed. 
12* 


274 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


Chloride  of  Gold  Developer. 

Distilled  water,  2  drachms. 

Chloride  of  gold,  2£  grains. 

Hydrochloric  acid,  -J  a  drop. 

This  is  a  more  rapid  developer  than  the  preceding.  This 
print  is  fixed  in  like  manner  by  water,  in  which  it  must  be 
well  washed,  and  afterward  dried.  When  dried  by  artifi- 
cial heat  the  vigor  of  the  print  is  increased.  Prints  that 
have  been  developed  by  the  solution  of  nitrate  of  silver  may 
be  immersed  in  the  gold  bath,  which  improves  their  tone. 

The  picture  may  be  developed,  also,  by  first  immersing 
the  prints  in  a  saturated  solution  of  bichloride  of  mercury, 
and  afterward  in  one  of  nitrate  of  silver.  In  this  case,  how- 
ever, the  time  of  exposure  is  increased. 

Pictures  may  be  obtained  also  by  floating  the  papers  on  a 
mixture  of  equal  quantities  of  nitrate  of  silver  and  nitrate  of 
uranium,  in  about  six  times  their  weight  of  water.  When 
dry,  they  are  exposed  beneath  a  negative.  In  this  case  the 
image  appears  as  in  the  positive  printing  process  with  chloride 
of  silver,  being  effected  by  the  decomposition  of  the  nitrate 
of  uranium,  which,  reacting  on  the  nitrate  of  silver,  decom- 
poses this  salt,  and  reduces  the  silver.  These  prints  require 
fixing  in  the  ordinary  fixing  bath  of  hyposulphite  of  soda, 
and  then  washing  as  usual. 

Process  for  Med  Pictures. 
Float  the  papers  for  four  minutes  in  the  preceding  bath  of 
nitrate  of  uranium,  drain  and  dry.    Next  expose  beneath  a 
negative  for  eight  or  ten  minutes,  then  wash  and  immerse  in 
the  following  bath  : 

Ferridcyanide  of  potassium,   30  grains. 

Rain-water,  3  ounces. 

In  a  few  minutes  the  picture  will  appear  of  a  red  color, 
which  is  fixed  by  a  thorough  washing  in  water. 

Process  for  Green  Pictures. 
Immerse  the  red  picture,  before  it  is  dry,  in  the  following 
solution : 

Sesquichloride  of  iron,  30  grains. 

Distilled  water,  3  ounces. 

The  tone  will  soon  change  to  a  green.  Fix  in  water,  and 
dry  before  the  fire. 

Process  for  Violet  Pictures. 

Float  the  papers  in  the  following  bath  for  three  or  four 
minutes : 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


275 


Water,  .... 
Nitrate  of  uranium, 
Chloride  of  gold, 


2  ounces. 
.  2  drachms. 
2  grains. 


Afterward  take  them  out  and  dry.  An  exposure  of  ten  or 
fifteen  minutes  will  produce  the  necessary,  reduction.  The 
picture  has  a  beautiful  violet  color,  consisting  of  metallic 
gold.    Wash  and  dry,  as  usual. 

Process  for  Blue  Pictures. 

Float  the  papers  for  a  minute  on  the  following  solution : 

Distilled  water,  5  ounces. 

Ferridcyanide  of  potassium,  1  ounce. 

Dry  in  the  dark-room,  and  then  expose  beneath  a  nega- 
tive until  the  dark  shades  have  assumed  a  deep  blue  color ; 
then  immerse  the  print  in  a  solution  of : 

Rain-water,  2  ounces. 

Bichloride  of  mercury,  1  grain. 

Wash  the  print,  and  then  immerse  it  in  a  hot  solution  of : 


This  process  aims  to  produce  a  picture  on  paper  either 
with  lampblack  or  some  other  fine,  impalpable  powder.  I 
shall  discuss  this  subject  as  distinct  from  photo-engraving  or 
photo-lithographic  operations,  although  the  two  processes 
are  based  upon  the  same  principle,  that  of  the  decomposi- 
tion of  the  bichromates  or  the  persalts  of  iron  when  exposed 
in  connection  with  organic  matter  to  -the  rays  of  the  sun. 
The  chloride  of  chromium  and  the  other  salts  of  chrome,  as 
well  as  the  sesqui-salts  of  iron,  are  subject  to  this  mode  of 
decomposition.  The  rationale  of  tbe  operation  appears  to  be 
this :  the  chromic  acid  of  the  chromate,  or  the  sesquioxide 
in  the  case  of  iron  is  reduced  by  light  into  the  sesquioxide 
of  chromium,  or  a  protosalt  of  iron,  and  thus  parts  with 
oxygen  which  is  communicated  to  the  organic  substance  with 
which  the  salts  were  mixed,  such  as  gelatine,  gum-arabic, 
etc.,  which  in  their  turn  become  changed  in  properties  as  to 
solubility  or  insolubility,  etc. 

Various  authors  have  experimented  in  this  direction ; 
Mungo  Ponton  first  indicated  the  principle.  We  are  indebt- 
ed for  the  most  interesting  results  in  carbon  printing  to 
Poitevin,  Gamier  and  Salmon,  Pouncy  and  Fargier.  In  the 
first  experiments  of  Poitevin,  a  chromate  was  employed  in 


Water,  .... 
Oxalic  acid,  .    .  . 

Again  wash  and  dry. 


Carbon  Process. 


4  ounces. 
4  drachms. 


276 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


connection  with  gum,  gelatine  or  albumen.  His  mode  of 
operation,  as  described  in  the  Traite  de  V Impression  Photo- 
graph  iqice  sans  sels  cV Argent  is  as  follows  : 

"I  apply  different  colors  either  liquid  or  solid  to  the  pa- 
per, fabric,  glass*  or  other  surfaces,  by  mixing  these  colors 
with  the  solution  above  mentioned,  (bichromate  of  potassa 
and  organic  matter,  etc.) 

"  The  photographic  impression,  on  this  prepared  surface,  is 
produced  by  the  action  of  light  passing  through  a  photo- 
graphic negative,  engraving  or  suitable  object,  or  finally  by 
means  of  the  camera.  It  is  then  washed  by  means  of  a 
sponge  and  an  abundance  of  water.  The  albumen  or  the 
organic  matter  becomes  insoluble  in  the  parts  where  the 
lights  have  acted,  and  the  picture  is  produced  by  the  color 
employed." 

A  second  method  is  described  as  follows : 

65  In  the  preparation  of  the  papers  I  cover  them  with  a 
concentrated  solution  of  one  of  the  substances  above  men- 
tioned (gum,  gelatine  and  the  like)  in  connection  with  a 
chromate ;  after  drying  I  submit  them  to  the  direct  rays  of 
the  sun  or  to  diffused  light  beneath  a  negative  of  the  object 
to  be  copied.  After  an  exposure,  which  varies  according  to 
circumstances,  I  apply  by  means  of  a  pad  or  a  roller  a  uni- 
form film,  either  of  typographic  or  lithographic  ink,  previ- 
ously diluted,  and  then  I  immerse  the  sheets  in  water.  It 
is  now  that  all  the  parts,  which  have  not  been  impressed  by 
light,  give  up  the  greasy  substance,  while  the  others  retain 
it  in  proportion  to  the  quantity  of  light  that  has  passed 
through  the  negative." 

The  principle  involved  in  these  two  operations  is  quite 
different,  although  the  result  is  the  same.  In  one  the  film  of 
gelatine,  etc.,  where  it  has  been  exposed  to  the  sun,  has  be- 
come insoluble  in  water,  and  consequently  retains  the  color- 
ing matter  from  being  carried  away  in  the  washing.  In  the 
other  case  the  film  that  has  received  the  impression  of  light, 
has  received  a  new  power,  that  of  adhering  to  the  greasy 
ink  applied  uniformly  to  the  whole  surface,  whilst  the  other 
parts,  having  no  attraction  for  this  ink,  allow  it  to  be  dis- 
solved off  when  floated  on  water. 

All  the  other  carbon  processes,  as  for  instance,  that  of 
Testud  de  Beauregard,  of  Pouncy,  Chardon,  Salmon  and 
Gamier,  Lafon  de  Camarsac,  and  of  Fargier,  are  mere  modi- 
fications of  Poitevin's  process,  with  but  little  amelioration. 

Testud  de  Beauregard  took  out  a  patent  for  his  process  in 
November,  1858.    It  will  be  unnecessary  to  describe  this 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


277 


process,  because  it  is  essentially  analogous  to  Poitevin's 
where  he  makes  use  of  printing  ink. 

Poimcifs  Process, 

Take  a  drachm  of  lampblack,  reduce  it  to  an  impalpable 
powder  and  pass  it  through  a  muslin  sieve  ;  mix  it  inti- 
mately with  half  an  ounce  of  a  concentrated  solution 
of  gum-arabic  and  the  same  quantity  of  a  similar  solu- 
tion of  bichromate  of  potassa.  Lay  on  a  uniform,  layer  of 
this  mixture  upon  a  piece  of  a  paper  fixed  on  a  stretcher, 
by  means  of  a  camel's  hair  pencil  ;  as  soon  as  it  is  dry,  it 
may  be  exposed  beneath  a  negative  to  the  sun's  rays  for  a 
number  of  minutes,  (from  four  to  eight.)  The  print  is  then 
immersed  in  water,  impression  side  downward,  and  left  for 
five  or  six  hours  in  this  fluid.  Finally  it  is  washed  beneath 
the  tap.  The  gum  and  the  coloring  matter  are  retained  in 
those  parts  that  have  been  impressed  ;  whilst  on  the  others 
they  are  dissolved  or  washed  off. 

Pouncy's  New  Carbon  Process. 

Take  a  sheet  of  tracing  paper,  made  transparent  by  var- 
nish or  oil,  and  coat  it  on  one  side  with  a  solution  of  gela- 
tine. When  dry  it  is  ready  to  receive  a  coating  of  printing 
ink  of  the  consistence  of  cream.  This  ink,  as  far  as  I  have 
been  informed,  consists  of  a  mixture  of  lampblack,  or  some 
similar  material,  together  with  asphaltum  or  bichromate  of 
potassa,  or  with  both.  The  quantity  of  the  latter  is  very 
small  by  reason  of  its  insolubility  in  the  other  ingredients. 
This  ink  is  brushed  over  the  surface  that  has  been  covered 
with  gelatine,  and  is  then  hung  up  to  dry.  This  part  of  the 
operation  has  to  be  performed  in  the  dark-room.  The  paper, 
when  dry,  may  be  preserved  for  months  unchanged,  if  not 
exposed  to  the  light. 

The  next  operation  is  to  expose  the  prepared  paper  be- 
neath a  negative  to  light.  Pouncy  has  availed  himself  of  a 
method  of  exposure  first  suggested  and  used  by  Fargier,  as 
will  be  seen  in  one  of  the  following  pages.  The  negative  is 
laid  in  the  printing-frame  as  in  the  ordinary  printing  of  pos- 
itives ;  upon  this  place  the  prepared  paper,  but  with  the 
white  surface  upon  the  film  of  the  negative,  and  the  surface 
covered  with  gelatine  and  sensitive  ink  away  from  it  or  on 
the  opposite  side. 

The  light,  therefore,  has  to  pass  both  through  the  nega- 
tive and  the  transparent  paper  before  it  arrives  at  the  sensi- 
tive film.    The  time  of  exposure  is  about  half  an  hour. 


278  PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


Wherever  the  light  impinges  upon  this  film,  it  indurates 
the  ink  and  renders  it  insoluble  in  turpentine  or  benzine.  In 
this  process  the  middle  tones  are  produced  with  great  ac- 
curacy and  beauty. 

After  exposure  there  is  no  apparent  change  in  the  film  ; 
but  when  the  paper  is  dipped  in  turpentine  the  soluble  parts 
are  all  dissolved  off.  The  paper  is  next  placed  in  a  second 
bath  of  turpentine  where  the  lights  are  thoroughly  cleansed  of 
ink. 

The  paper  is  then  taken  out  and  dried.  The  paper  being 
transparent,  the  picture  is  seen  through  it,  and  then  regard- 
ed as  a  true  picture,  free  from  inversion.  These  prints  can 
be  used  as  transparencies,  or  can  be  transferred  to  cardboard 
or  stone.  In  the  former  case  they  look  like  wood-cuts  or  en- 
gravings, combining  at  the  same  time  all  the  beauty  of  the 
photograph. 

This  discovery  of  Pouncy's  has  been  published  without 
the  necessary  details,  just  as  these  sheets  are  passing  through 
the  press ;  but  if  the  results  are  as  stated  by  good  authori- 
ties, it  may  be  regarded  as  the  great  discovery,  not  only  01 
the  year,  but  of  the  age.  Neither  silver  nor  gold  is  re- 
quired in  the  process — the  prints  appear  in  printing  ink 
after  developing,  fixing,  and  washing  in  turpentine. 

Processes  of  Salmon  and  Gamier. 

For  one  of  these  processes  a  part  of  the  Luynes  second 
prize  was  assigned  to  the  authors  in  1858.  Their  other  pro- 
cess was  not  brought  into  competition,  although  it  was  pa- 
tented. (Poitevin  took  the  first  gold  prize.)  In  both  pro- 
cesses a  transparent  positive  is  employed  instead  of  a  nega- 
tive. 

]STo.  1.  —  Dissolve  thirty  drachms  of  loaf-sugar  in  thirty 
drachms  of  water,  then  add  seven  drachms  and  a  half  of 
neutral  bichromate  of  ammonia,  pulverized  and  dissolved 
in  a  mortar.  To  this  mixture  add  ten  drachms  of  the 
white  of  egg  previously  well  beaten  up  together  with 
a  few  grains  of  the  bichromate.  As  soon  as  all  these 
ingredients  have  been  very  intimately  mixed,  the  solution 
is  passed  through  a  linen  filter  for  use.  Tn  the  mean 
while  the  paper  is  fixed  on  a  board  by  means  of  tacks, 
and  then  brushed  over  with  the  above  mixture.  Take  care 
to  use  of  the  mixture  only  just  enough  to  cover  the  surface 
in  order  thus  to  obviate  streaks  and  other  similar  imperfec- 
tions. The  paper  is  then  removed  and  dried  before  the  fire, 
taking  care  not  to  bring  it  too  near,  and  to  present  the 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


279 


posterior  side  to  the  heat.  This  part  of  the  operation  is  soon 
finished.  It  is  then  exposed  beneath  a  positive  to  the  rays  of 
the  sun  for  fifteen  or  twenty  minutes.  After  the  expiration 
of  this  time  the  image  is  quite  visible ;  the  paper  is  again  heat- 
ed before  the  fire,  which  appears  to  continue  the  action  of  light, 
and  thus  becomes  the  means  of  modifying  the  intensity  of 
the  shades.  It  is  now  fixed  a  second  time  upon  the  board, 
and  fine  ivory  black  is  brushed  over  the  surface  with  a  flat, 
moderately  soft  and  flexible  camel's  hair  brush.  The  film 
of  ivory  black  is  afterward  uniformly  spread  by  means  of  a 
soft  pad  of  cotton  all  over  the  surface,  after  which  the  paper 
is  detached  from  the  board  and  presented  for  a  few  seconds 
to  the  fire.  This  being  done,  the  paper  is  cautiously  immersed 
in  water,  picture-side  upward,  and  left  there  for  a  quarter 
of  an  hour,  moving  it  about  gently  at  intervals.  As  soon  as 
it  is  supposed  that  the  soluble  portions  of  the  bichromate 
have  been  removed  by  the  water,  the  paper  is  withdrawn. 
Finally,  in  order  to  improve  the  whites,  the  paper  is  im- 
mersed in  a  bath  containing  ten  ounces  of  water  and  half  an 
ounce  of  concentrated  sulphurous  acid.  This  operation  has 
to  be  performed,  in  like  manner  with  the  preceding,  with 
great  care,  otherwise  the  coloring  matter  is  liable  to  be  carried 
off  from  the  parts  which  are  insoluble,  for  the  film  does  not 
adhere  with  much  tenacity.  The  object  of  this  final  immer- 
sion is  to  remove  a  number  of  yellow  and  gray  patches  in 
the  lights  ;  with  the  greatest  care,  however,  it  is  very  difficult 
to  get  rid  of  numerous  small  particles  of  charcoal  imbedded 
as  it  were  in  the  porous  structure  of  the  paper.  After  this 
oj3eration  the  paper  is  taken  and  dried. 

Sulphurous  acid  may  be  prepared  for  the  preceding  oper- 
ation, by  heating  a  mixture  of  sulphuric  acid  and  small 
fragments  of  wood,  such  as  chips  or  matches,  in  a  retort. 
The  vapor  thus  produced  is  sulphurous  acid,  which  can  be 
condensed  in  cold  rain-water  to  saturation. 

No.  2. — In  the  second  process  a  thick  solution  of  citrate 
of  iron  is  spread  evenly  with  a  soft  linen  pad  over  the  surface 
of  a  sheet  of  satin  paper.  The  paper  is  then  dried  in  the 
dark-room.  It  is  next  exposed  beneath  a  transparent  posi- 
tive from  ten  to  thirty  minutes  to  the  rays  of  the  sun,  by 
which  an  image  is  made  apparent.  This  is  intensified  or 
made  more  vigorous  by  the  following  application.  Fix  the 
paper  on  a  board  with  tacks  and  then  with  a  cotton  pad  dab 
the  surface  over  uniformly  with  an  impalpable  powder  of 
carbon  or  any  other  color.  At  first  no  change  is  apparent, 
but  by  breathing  upon  the  surface,  those  parts  that  have  not 


280  PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


been  impressed  by  lig]  it,  being  more  or  lesshygrometricin  pro- 
portion to  the  actinic  action,  attract  the  humidity  and  at  the 
same  time  the  coloring  material,  which  exhibits  the  image. 
The  parts  through  which  light  has  penetrated,  being  no 
longer  deliquescent,  or  at  least  only  partially  so,  reject  the 
carbonaceous  materials,  and  these  are  swept  away  together 
with  the  unaltered  citrate  in  the  process  of  washing  and 
fixing.  The  prints  are  afterward  dried  and  varnished  if 
thought  necessary.  The  addition  of  sugar  to  the  citrate  in 
this  process  is  recommended  by  Poitevin. 

All  these  processes  are  more  or  less  defective,  producing 
prints  devoid  of  the  middle  tones.  This  arises  from  the 
circumstance  that  the  image  is  in  general  a  mere  surface 
picture,  and  especially  as  regards  the  middle  tints.  In  the 
washing,  therefore,  these  are  apt  to  be  annihilated  together 
with  the  soluble  film  beneath  them.  This  defect  had  been 
noticed  and  the  cause  assigned  by  Laborde  as  well  as  by 
Poitevin  ;  and  it  is  probable  that  Fargier  eliminated  his  pro- 
cess on  the  hints  thus  published.  The  difference  in  his  mode 
of  manipulating  consists  essentially  in  separating  the  film 
containing  the  image  from  the  glass  upon  which  it  was  form- 
ed, and  in  fixing  it  on  a  piece  of  gelatinized  paper  the  other 
side  up.  The  chemical  and  actinic  part  of  the  operation  re- 
mains the  same  as  in  Poiteviirs. 

Fargier* s  Process, 

Make  a  mixture  of  two  drachms  of  white  gelatine  dissolv- 
ed in  two  ounces  and  a  half  of  water,  and  fifteen  grains  of 
lampblack,  (previously  washed  with  carbonate  of  soda,  and 
afterward  with  hydrochloric  acid,  in  order  to  remove  all 
fatty  or  resinous  matter ;)  to  this  mixture  add  a  few  drops 
of  ammonia  in  order  to  decompose  the  alum  contained  in 
the  gelatine  and  finally  fifteen  grains  of  bichromate  of 
potassa.  The  mixture,  when  the  ingredients  are  thor- 
oughly dissolved,  is  filtered  through  a  linen  cloth,  and  after 
it  is  made  hot,  it  is  poured  upon  a  properly  cleaned  glass, 
and  the  films  dried  by  a  gentle  heat. 

The  glass,  thus  prepared,  is  exposed  for  a  few  seconds  to 
the  light,  and  then  beneath  a  negative  to  the  rays  of  the  sun. 

The  first  exposition  to  light  for  a  few  seconds  is  to  render 
the  whole  surface  of  the  gelatine  slightly  insoluble.  The 
second  exposure  beneath  a  negative  produces  an  insolubility 
more  or  less  deep  according  to  the  luminous  intensity  and 
its  duration.  It  will  be  easily  conceived  that  the  two  sur- 
faces of  the  gelatine  film,  that  is,  the  npper  surface  and  the 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


281 


one  adhering  to  the  glass,  are  in  very  different  conditions, 
the  former  being  almost  totally  soluble,  excepting  here  and 
there  where  the  intensity  of  the  rays  has  penetrated  the  whole 
substance  ;  whereas  the  exterior  surface,  as  before  remarked, 
is  insoluble.  The  parts  between  these  surfaces  are  more  or 
less  soluble  according  to  the  quantity  and  intensity  of  the 
light  that  has  passed  through  the  negative.  It  will  be  seen, 
therefore,  from  these  conditions  of  things,  that  the  operation 
if  washing,  in  order  to  be  effectual,  ought  to  be  performed 
on  the  under  surface.  The  film  consequently  is  removed  from 
the  glass  and  transferred  in  the  following  manner  : 

Flow  the  film  on  the  glass  plate  with  two  coats  of  collodion, 
and  then  immerse  it  in  a  dish  of  lukewarm  water.  The  col- 
lodion will  soon  be  detached  together  with  the  gelatine  film, 
which  will  float  in  the  water.  The  film  is  allowed  to  remain 
until  all  the  soluble  parts  are  dissolved  off,  together  with 
the  coloring  matter  which  they  contain.  By  this  mode  of 
proceeding  the  most  delicate  half-tones  remain  attached  to 
the  collodion,  and  the  image  is  brought  out  very  perfectly. 
Whilst  in  this  condition  in  the  water  a  piece  of  paper  already 
prepared  With  gelatine  is  brought  carefully  beneath  the  float- 
ing film  and  then  lifted  out  of  the  water  and  stretched  upon 
a  board.  The  film,  carefully  adjusted  on  the  gelatinized  sur- 
face of  the  paper,  soon  adheres  to  it,  and  may  thus  be  dried. 

Carbon  Processes  with  the  Salts  of  Iron. 
Without  recapitulating  all  the  various  processes  arising 
out  of  the  use  of  the  salts  of  iron,  I  may  here  mention  that 
Poitevin  has  employed  the  gallate  of  iron  and  the  sesqui-  * 
chloride ;  and  that  others,  following  in  his  steps,  have  been 
more  or  less  successful  in  the  same  domain  of  experimenta- 
tion. I  will  give  two  examples  only,  and  refer  the  reader 
for  more  ample  information  to  Poitevin's  interesting  treatise. 

JVb.l. — Process  with  Sesquichloride  of  Iron  and  Tartaric 

Acid. 

Make  two  solutions  as  follows : 

^    j    j  Sesqui  chloride  of  iron,    .    .    .    .  5 1  drachms. 

*   '    (  Water,   15  drachms. 

2    (  Tartaric  acid,   2  drachms. 

1  Water,   15  drachms. 

Filter  each  solution  separately,  then  mix  and  add  two 
ounces  and  a  half  more  water.  Keep  the  solution  in  the 
dark,  and  use  it  until  exhausted. 

The  image  with  carbon  or  any  other  colored  and  inert 


282  PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


powder  is  formed  on  glass.  For  this  purpose  Poitevin  re- 
commends such  glass  as  is  used  for  stereoscopic  slides,  being 
ground  on  one  side.  If  the  glasses  have  been  used  before, 
they  are  cleaned  by  the  ordinary  means  recommended. 
Each  glass  is  then  flowed  with  the  sensitizing  solution  jusfc 
prepared,  in  the  same  way  as  with  collodion  or  albumen, 
and  the  excess  is  poured  off  at  each  corner.  They  are  then 
reared  on  one  corner  on  pieces  of  bibulous  paper,  inclining 
at  an  angle  of  60°,  with  the  sensitized  surface  downward. 
It  is  better  to  dry  the  plates  by  rearing  them  up  near 
some  heated  surface,  otherwise  the  operation  of  desiccation 
will  be  very  tedious.  This  operation  must  be  performed  in 
the  dark-room.  The  property  of  the  dry  plates  is  this : 
by  the  influence  of  light  they  become  hydroscopic.  The 
plates  so  prepared  will  keep  for  months  in  boxes,  as  was 
to  be  expected,  inasmuch  as  the  persalts  of  iron  have  a 
tendency  in  the  dark  rather  to  peroxidize  than  to  be  reduced 
to  protosalts. 

A  plate  is  exposed  beneath  an  ordinary  negative  varnished 
with  copal  dissolved  in  alcohol ;  all  other  varnishes,  such  as 
those  prepared  with  benzine,  gum,  gelatine,  etc.^  would  be 
injurious.  The  film  of  the  prepared  glass  and  of  the  negative 
are  in  juxtaposition,  and  are  placed  together  with  great  care. 
The  time  of  exposure  is  about  the  same  as  in  the  common 
printing  process.  This  has  to  be  learned  by  practice  ;  it  is 
better  to  give  too  much  time  than  too  little,  because  the  de- 
velopment can  be  stopped  as  soon  as  the  image  has  sufficient- 
.  ly  appeared.  When  taken  from  the  printing  frame  the  picture 
is  already  visible,  white  upon  a  yellow  ground.  It  is  exposed 
in  the  dark-room  to  the  influence  of  the  air,  when  it  will  be 
found  that  all  those  parts  that  have  received  the  luminous 
action  will  become  moist.  In  a  few  minutes  the  filmwill  be 
ready  to  receive  the  first  application  of  the  carbonaceous  or 
other  inert  colored  material. — By  putting  away  the  plates 
when  taken  from  the  printing  frame  in  well-closed  boxes, 
the  development  may  be  postponed. — The  development  is 
effectuated  by  dipping  a  very  soft  camel's  hair  pencil  in  the 
fine  impalpable  powder  and  then  dabbing  or  rubbing  it  gent- 
ly over  the  surface  of  the  impressed  plates ;  the  image  will 
soon  begin  to  appear,  the  coloring  material  adhering  only  to 
those  parts  that  have  become  hydroscopic  by  the  action  of 
the  light,  and  consequently  in  proportion  to  the  luminous 
impression.  In  general  the  half-tones  do  not  appear  by  the 
first  application  of  the  powder,  and  it  is  better  when  this  is 
so ;  for  if  the  plate  took  up  the  color  too  quickly,  it  would 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


283 


be  a  sign  that  the  exposure  had  been  too  long.  A  second 
application  of  the  powder  is  made,  and  then  a  third,  and  so 
on,  until  the  image  is  brought  out  in  perfect  harmony  ,  of 
light  and  shade.  The  operation  may  be  stopped  midway 
without  any  injury  to  the  final  development,  which  may  be 
completed  at  any  convenient  time.  It  is  very  easy  to  follow 
the  progress  of  development  by  placing  the  plate  image  side 
downward  on  a  sheet  of  paper,  or  by  regarding  it  by  trans- 
mitted light ;  but  seen  so,  it  is  always  more  feeble  than  by 
reflected  light.  It  is  also  easy  to  accelerate  certain  portions 
which  are  slow  in  appearing ;  all  that  is  required  is  to  moist- 
en them  with  the  breath,  and  then  go  over  the  parts  with  the 
pencil  dipped  in  the  carbonaceous  powder.  As  soon  as  the 
image  is  perfect,  it  may  be  retained  on  the  plate  by  means 
of  a  coat  of  varnish,  and  thus  be  used  as  a  transparent  posi- 
tive, without  any  washing  or  fixing.  If  instead  of  lampblack 
or  vegetable  colors,  metallic  oxides  or  enamel  powders  were 
to  be  applied  to  the  sensitized  glass  plate,  these  coloring  sub- 
stances may  be  melted  in  a  muffle,  which  communicates  to  the 
surface  of  the  glass  plate  a  perfectly  unalterable  picture,  sim- 
ilar to  glass-painting  ;  the  same  mode  of  operation  may  be 
applied  to  plates  of  porcelain.  In  case,  however,  it  is  required 
to  transfer  the  print  to  paper,  the  operation  may  be  perform- 
ed either  immediately  or  a  long  time  afterward. 

To  transfer  the  Carbon  Print  from  Glass  to  Paper. 

This  operation  is  extremely  simple,  and  presents  no  diffi- 
culty. Coat  the  film,  containing  the  picture,  with  common 
plain  collodion,  of  a  consistence  suitable  for  photographic 
purposes,  then  immerse  the  plate  in  water  until  the  oily  as- 
pect of  the  film  has  disappeared.  Next  pour  upon  the  col- 
lodion surface  water  acidulated  with  hydrochloric  acid  ; 
repeat  the  operation  two  or  three  times.  The  film  immedi- 
ately in  contact  with  the  glass  is  rendered  soluble  in  water 
by  means  of  the  acid,  and  the  adherence  of  the  collodion  to 
the  glass  is  at  the  same  time  destroyed.  The  acid  is  then 
thoroughly  removed  by  washing  in  several  waters,  and  then 
a  piece  of  paper,  covered  with  a  layer  of  gelntine  on  one  side 
and  previously  moistened,  is  placed  upon  the  collodion  and 
brought  into  contact  with  it  by  means  of  a  large,  broad  and 
soft  pencil,  which  is  moved  over  it  in  all  directions.  As  soon 
as  the  contact  is  complete  and  all  bubbles  of  air  have  been 
removed,  the  whole  is  left  to  dry  spontaneously.  In  the  act 
of  drying  the  gelatinized  paper  separates  from  the  glass  of 
itself,  carrying  with  it  the  film  of  collodion  in  firm  adhesion 


284  PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


to  the  picture.  All  that  now  remains  to  be  done  is  to  var- 
nish the  surface.  Copal  varnish  is  suitable  for  this  purpose, 
because  it  lies  upon  the  surface  of  the  image  without  pene- 
trating the  film  of  collodion  or  gelatine,  and  consequently 
never  arrives  at  the  paper  beneath.  The  prints,  thus  obtain- 
ed, have  a  very  delicate  and  velvety  appearance,  the  only 
drawback  being  that  of  lateral  inversion  like  the  negative, 
unless  the  latter  has  been  specially  prepared  beforehand. 
But  the  picture  can  be  produced  without  any  lateral  inver- 
sion, not  only  by  having  a  negative  in  the  right  conditions, 
but  by  the  following  somewhat  complicated  manipulation, 
although  equally  as  easy  as  the  preceding.  In  this  case, 
the  collodion  is  applied  as  before,  the  immersion  in  water 
and  the  flowing  with  acidulated  water  are  performed,  and 
then  a  piece  of  moistened  paper,  smaller  in  size  than  the 
plate,  is  brought  into  contact  with  the  collodion  film,  in  the 
same  way  as  the  gelatinized  paper  was  made  to  adhere. 
The  border  of  film  all  round  the  paper  is  now  raised  and 
folded  over  the  edges  of  the  paper,  which  when  raised  with 
caution  carries  the  whole  detached  film  from  the  glass.  A 
piece  of  paper  covered  with  gelatine  and  larger  than  the  plate 
is  now  moistened,  upon  this  the  detached  print  is  brought 
into  contact,  pressed  into  perfect  adhesion  by  means  of  the 
soft  brush,  and  then  the  borders  of  the  film  around  the  edges 
of  the  first  paper  are  folded  back,  when,  seizing  an  angle 
of  the  first  paper,  it  is  easily  raised  from  the  collodion  film. 
The  picture  now  is  no  longer  inverted,  and  is  besides  fixed, 
the  coloring  matter  or  image  proper  lying  protected  between 
two  films,  one  of  collodion  and  the  other  of  gelatine.  With 
a  tenacious  collodion  this  operation  of  double  transfer  is  al- 
ways successful ;  it  takes  in  fact  longer  to  describe  it  than  to 
perform  it  ;  as  to  the  simple  transfer,  it  always  succeeds, 
whatever  may  be  the  quality  of  the  collodion. 

This  process,  after  all,  is  very  simple  and  almost  always 
certain ;  besides  this,  it  entails  but  little  expense  and  re- 
quires less  delicacy  of  manipulation  than  other  photographic 
processes. 

For  vitrification  or  enamel  operations,  it  possesses  a  great 
advantage  arising  from  the  facility  of  folding  the  collodion 
film,  retaining  the  picture  upon  curved  as  well  as  upon  plain 
surfaces. 

Another  property  of  the  surfaces  prepared  with  the  sesqui- 
chloride  of  iron  and  tartaric  acid  is  this  :  fatty  substances, 
such  as  printing  inks,  applied  after  the  luminous  impression 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER.  285 


through  a  negative,  adhere  only  to  those  parts  that  have  not 
been  modified  by  light. 

Almost  all  vegetable  colors  may  be  used  in  this  process ; 
it  will  be  evident  therefore  that  pictures  resisting  all  change 
from  the  atmosphere  or  from  time,  may  be  obtained  of  any 
color  that  may  please  the  fancy. 

Printing  directly  on  Paper  by  means  of  the  Sesquichloride 
of  Iron  and  Tartaric  Acid. 

This  is  a  new  process  of  Poitevin's.  Five  or  six  parts  of 
gelatine  are  dissolved  in  a  hundred  parts  of  water ;  this  so- 
lution is  colored  with  a  sufficient  quantity  of  lampblack  or 
any  other  inert  color.  Each  sheet  of  paper  is  floated  on  this 
solution,  which  is  kept  lukewarm  on  a  water-bath.  By  this 
means  a  very  uniform  film  of  color  is  communicated  to  one 
side  of  the  paper,  which  is  afterward  placed  flat  on  a  hori- 
zontal surface  with  the  colored  side  uppermost,  and  allowed 
to  dry  spontaneously.  In  this  way  a  large  number  of  sheets 
may  be  prepared  beforehand. 

In  order  to  sensitize  them  they  are  immersed  in  a  bath 
containing  a  solution  of  sesquichloride  of  iron  and  tartaric 
acid  in  the  proportion  of  ten  parts  of  the  sesquichloride  01 
iron,  one  hundred  parts  of  water  and  three  parts  of  tartaric 
acid.  The  papers  are  then  allowed  to  dry  in  the  dark.  By 
this  treatment  the  film  of  gelatine  has  become  completely 
insoluble,  even  in  boiling  water. 

These  films  receive  the  actinic  impressions  through  a  trans- 
parent positive ;  and  in  the  parts  where  the  light  acts,  the 
film  becomes  soluble  in  hot  water  proceeding  from  the  sur- 
face of  the  film  in  contact  with  the  transparent  positive. 

After  the  paper  has  been  in  this  way  exposed  to  the  sun, 
if  the  positive  is  not  very  intense,  (which  is  preferable  in  this 
kind  of  print,)  it  is  immersed  in  hot  water ;  then  all  the 
parts  that  have  undergone  the  solar  influence  are  dissolved 
in  proportion  to  the  quantity  of  light  that  has  permeated 
the  glass  positive.  In  the  places  which  correspond  with  the 
lights  of  the  positive,  the  blackened  or  colored  surface  is 
dissolved  to  the  surface  of  the  paper,  and  will  leave  perfect 
whites ;  whereas  in  the  half-tints,  only  a  certain  portion  of 
the  film  will  disappear,  proceeding  from  the  surface,  and 
these  half-tones  will  be  reproduced  by  the  greater  or  less 
thickness  of  the  film  of  gelatine  remaining  insoluble.  Now 
as  this  part  is  in  immediate  contact  with  the  surface  of  the 
paper,  it  can  not  be  carried  away  in  washing.  As  to  those 
parts  of  the  positive  which  are  completely  black,  they  will 


286 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


be  produced  by  the  total  thickness  of  the  primitive  film.  All 
that  is  required  to  finish  the  print  is  to  allow  it  to  dry,  and 
then  to  wash  it  in  acidulated  water  in  order  to  get  rid  of  the 
salts  of  iron,  afterward  to  pass  it  through  several  waters, 
and  finally  to  allow  it  to  dry  spontaneously. 

Photographic  Engraving. 
It  is  a  curious  fact  that  experiments  in  photographic  en- 
graving gave  rise  to  photography  itself.  The  idea,  the  most 
prominent  in  the  mind  of  Nicephore  Niepce,  when  he  com- 
menced his  indefatigable  researches  in  1813,  was  not  only  to 
fix  the  image  obtained  by  the  camera  obscura  on  a  plate  oi 
metal,  but  to  convert  this  plate  into  an  engraving  from  which 
to  receive  prints  by  the  press.  After  the  partnership  con- 
cluded between  Niepce  and  Daguerre,  this  idea  appears  to 
have  been  abandoned;  and  an  early  death  removed  the 
former,  the  real  originator  of  much  that  is  valuable  in  pho- 
tography, before  he  perfected  the  process  which  he  left  us. 
This  process,  together  with  a  great  deal  that  is  interesting 
in  photographic  engraving,  will  be  found  at  length  in  a  small 
pamphlet  published  by  his  indefatigable  nephew,  Niepce  de 
Saint- Victor,  the  Traite  Pratique  de  Gravure  Heliograph- 
ique,  in  1856. 

The  various  ways  that  have  been  taken  to  come  to  one 
and  the  same  result,  that  of  obtaining  a  metallic  plate,  re- 
sembling an  engraved  plate,  from  which  to  receive  prints 
exactly  in  the  same  way  as  with  the  engraved  plate,  take 
their  origin  either  from  the  Iodo-mercurio-type  or  plated  cop- 
per of  Donne,  the  bichromotype  of  Talbot,  or  the  asphalto- 
type  of  Nicephore  Niepce,  if  I  may  thus  be  allowed  to  create 
new  names  to  represent  these  three  classes.  Without  adher- 
ing to  historical  dates,  I  will  simply  recount  what  has  been 
accomplished  in  each  class. 

Engraving  on  the  Daguerreotype  Plate. 

The  first  attempts  that  were  made  to  convert  the  daguer- 
reotype into  an  engraved  plate  by  an  etching  liquid,  were 
those  of  Dr.  Donne.  He  first  went  round  the  edge  of  the 
plate  with  a  varnish  or  wax,  making  a  ledge  so  as  to  retain 
the  etching  fluid.  This  fluid  consisted  of  aquafortis  diluted 
with  four  parts  of  water,  which,  when  poured  upon  the  plate 
immediately  after  the  image  was  fixed,  but  not  gilt,  attacked 
the  silver  parts,  without  injuring  or  altering  the  whites.  As 
soon  as  the  etching  was  supposed  to  have  advanced  far 
enough,  the  plate  was  well  washed,  and  the  varnish  or  wax 
removed  from  the  edges.    It  was  then  ready  to  print  from. 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


287 


The  specimens  obtained  by  the  engraver's  press  from  such- 
plates  were  not  very  satisfactory ;  and  the  softness  of  the 
silver  film  precluded  the  possibility  of  printing  more  than  a 
few  dozen  from  the  same  plate. 

Process  of  Fizeau. 

This  process  is  similar  to  that  of  Donne,  but  it  proceeds 
further,  and  thus  overcomes  two  very  great  imperfections  in 
Donne's  plates  :  the  want  of  depth  in  the  parts  etched,  and 
the  extreme  softness  of  the  silver  film.  I  will  give  the  pro- 
cess as  described  by  the  originator  : 

"  A  mixed  acid,  composed  of  nitric,  nitrous  and  hydro- 
chloric, (the  last  two  may  be  replaced  by  nitrite  of  potassa 
and  common  salt,)  is  endowed  with  the  requisite  properties, 
which  is  common  to  a  solution  of  bichloride  of  copper,  but 
in  a  manner  less  perfect. 

"  If  a  daguerreotype,  whose  surface  is  very  pure,  be  sub- 
mitted to  the  action  of  this  acid,  especially  when  hot,  the 
white  parts  are  not  altered,  while  the  blacks  are  attacked 
with  the  formation  of  chloride  of  silver,  which  adheres  to 
the  surface  and  prevents  any  further  action  of  the  acid  by 
reason  of  its  insolubility. 

"Ammonia  is  then  poured  upon  the  plate,  which  removes 
the  film  of  chloride,  and  thus  presents  a  fresh  surface  to  the 
action  of  the  acid.  By  this  means  the  depth  of  the  shades 
can  be  increased. 

"  By  operating  in  this  way  for  several  times,  the  daguerreo- 
type becomes  converted  into  an  engraved  plate  of  great 
perfection,  but  in  general  not  possessed  of  sufficient  depth, 
so  that  the  prints  on  paper  are  not  vigorous  enough.  It  has 
been  found  necessary,  therefore,  to  adopt  other  means  of  in- 
creasing the  depth  of  the  shades.  This  operation  consists  in 
gilding  the  prominent  parts  or  the  lights  of  the  engraving, 
and  to  leave  the  silver  in  the  etched  parts  intact ;  by  which 
means  the  depth  of  the  etching  can  be  increased  afterward 
by  a  simple  solvent  of  silver. 

"  In  order  to  obtain  this  result,  the  plate  engraved  as  just 
described  is  rubbed  over  with  a  drying  oil,  as  for  instance 
linseed  oil,  then  wiped  in  the  manner  of  copper-plate  print- 
ers. In  this  way  the  oil  remains  in  the  cavities  alone  and 
forms  a  varnish  which  soon  dries. 

"Gold  is  next  deposited  by  galvanism  upon  all  the  parts  of 
the  plate  excepting  those  filled  with  the  linseed  varnish, 
which  is  afterward  removed  by  caustic  potassa.  The  result 
of  this  is  that  all  the  prominent  parts  of  the  plate  are  protected 


288 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


•by  a  film  of  gold  ;  whereas  the  excavated  parts  present  de- 
nuded silver. 

"  It  is  now  easy  by  means  of  nitric  acid  to  act  upon  these 
hollow  parts  alone,  and  thus  increase  the  depth  ad  libitum. 
Previous  to  this  treatment,  however,  the  plate  is  covered  by 
what  is  denominated  by  engravers  the  resin-grain^  which 
produces  in  the  metal  those  numerous  inequalities  denomi- 
nated aqua-tinta  granulations. 

"From  the  result  of  these  two  operations  the  daguerreo- 
type plate  is  transferred  into  an  engraved  plate  resembling 
the  aqua-tinta  plates,  which  like  these  is  in  a  condition  by 
impression  to  furnish  a  number  of  prints. 

"  But  since  silver  is  a  very  soft  metal,  the  number  of  im- 
pressions would  be  very  limited,  if  some  very  simple  means 
were  not  devised  to  remedy  the  speedy  destruction  of  the 
photographic  plate  when  submitted  to  the  operations  of  the 
press. 

"  This  end  is  attained,  previous  to  handing  the  plate  over 
to  the  printer,  by  covering  its  surface  with  a  film  of  cop- 
per by  the  electrolitic  process.  In  this  way  it  is  evident 
that  the  film  of  copper  alone  bears  the  wear  and  tear  pro- 
duced by  the  labor  of  the  pressman.  If  this  film  should 
happen  to  be  damaged  to  any  considerable  degree,  it  may 
be  entirely  dissolved  oif  by  means  of  a  dilute  acid,  without 
injuring  the  silver  on  which  it  is  deposited,  when  the  plate 
may  again  be  covered  with  copper,  and  rendered  as  good 
as  new." 

Process  of  Talbot, 
Plates  of  copper,  steel  or  zinc  are  employed  in  this  pro- 
cess. These  are  first  washed  over  with  a  dilute  solution  of 
sulphuric  acid  in  order  to  remove  the  film  of  oxide,  then  well 
rubbed  with  a  mixture  of  carbonate  of  soda,  and  well  dried. 
A  solution  of  bichromate  of  potassa  and  gelatine  is  then 
flowed  over  the  surface,  and  dried  by  the  application  of  heat 
until  the  film  assumes  a  beautiful  yellow  color.  This  opera- 
tion is  performed  in  the  dark-room. 

-lt    -i      (  Gelatine,  1  drachm. 

JN0'1-     \  Water,  2£  ounces. 

No.  2.    ■{  Saturated  solution  of  bichromate  of  potassa,  .    4  drachms. 

Mix  the  two  solutions  and  filter.  The  mixture  will  keep 
for  some  time.  In  summer  it  is  sufficiently  fluid ;  but  in 
winter  it  requires  to  be  warmed  before  it  is  flowed  upon  the 
plates.  It  must  be  preserved  in  a  dark  place.  The  propor- 
tions above  given  are  found  to  work  well,  but  they  may  be 


FEINTING  WITHOUT  THE  SALTS  OF  SILVER.  289 


changed,  however,  without  altering  the  result.  The  color 
of  the  film  is  pale  yellow  and  generally  bordered  with  nar- 
row fringes  of  prismatic  colors.  If  the  whole  surface  is 
covered  with  this  prismatic  appearance,  it  indicates  that  the 
film  is  very  thin,  perhaps,  if  any  thing,  too  much  so  for  suc- 
cessful manipulation. 

The  transparent  positive  or  other  object  is  now  placed  in 
the  printing  frame  and  the  prepared  plate  upon  it.  An  al- 
bumen photograph  is  the  best  adapted  for  such  operations, 
because  the  film  is  the  least  liable  to  be  damaged.  The  two 
films  are  in  juxtaposition.  An  exposure  of  two  or  three 
minutes  to^the  rays  of  the  sun  will  produce  a  picture  which 
will  appear  yellow  on  a  brownish  background.  A  longer 
exposure  is  required  in  diffused  light ;  the  amount  of  which 
will  have  to  be  modified  by  experience. 

The  next  operation  consists  in  covering  the  film  of  the 
plate  when  removed  from  the  printing-frame  with  very  fine 
copal  or  resin  powder.  This  part  of  the  work  has  to  be  per- 
formed with  great  care  and  uniformity.  It  is  frequently  ef- 
fected by  placing  a  heap  of  the  finely  pulverized  material  on 
the  bottom  of  the  box  and  then  with  a  pair  of  bellows  to 
make  a  cloud  of  the  dust  in  which  the  plate  is  placed.  The 
object  of  this  operation  is  to  communicate  to  the  plate  the 
aqua-tinta  granulation.  If  the  film  of  copal  or  resin  be  too 
thick,  the  etching  fluid  will  not  be  able  to  penetrate  to  the 
metallic  plate  beneath.  The  plate  thus  covered  with  the 
powder  is  heated  over  an  alcohol  lamp  in  order  to  melt  the 
copal.  The  fusion  is  known  to  be  effected  by  a  change  in 
the  color.  The  plate  is  then  allowed  to  cool.  The  ordinary 
way  of  producing  an  aqua-tinta  foundation  is  to  project  the 
resinous  powder  on  the  denuded  surface  of  the  metal ;  in 
this  case  it  is  on  the  surface  of  the  gum  itself,  and  it  is  found 
to  act  well. 

The  etching  fluid  is  prepared  as  follows  :  Saturate  hydro- 
chloric acid  with  sesquioxide  of  iron  by  means  of  heat.  The 
solution  is  filtered  and  evaporated  until  when  cooled  it  be- 
comes a  concrete  mass,  which  is  preserved  in  well-stoppered 
bottles.  It  is  a  very  deliquescent  salt.  With  this  salt  pre- 
pare three  solutions  in  the  following  manner : 

No.  1.  Saturated  solution  of  sesquichloride  of  iron  in 
water. 

No.  2.  Contains  five  or  six  parts  of  No.  1  to  one  of  water. 
No.  3.  Contains  equal  portions  of  No.  1  and  water. 
The  stronger  the  solution,  the  less  effective  in  etching ; 
the  right  strength  can  be  learned  only  by  experience.  Make 
"l3 


290 


PKINTIXG  WITHOUT  THE  SALTS  OF  SILVEE. 


a  trial  as  follows  :  Pour  a  small  quantity  of  ]STo.  2  upon  the 
plate  and  spread  it  with  a  camel's  hair  pencil.  It  is  not 
necessary  to  have  an  elevated  border  of  wax  around  the 
plate,  because  but  a  very  small  quantity  of  fluid  is  used,  and 
there  is  no  danger  of  its  flowing  over  the  edges  of  the  plate. 
The  etching  fluid  penetrates  the  gelatine  where  the  light  has 
not  acted,  and  this  penetration  is  in  proportion  to  the  defi- 
ciency of  the  luminous  action.  On  this  remarkable  property 
is  founded,  in  a  great  measure,  the  art  of  photographic  en- 
graving. After  a  minute  or  so,  the  engraving  begins  to  show 
itself  by  turning  dark,  brown  or  black  ;  and  soon  the  effect 
extends  over  the  whole  plate.  The  details  of  the  picture 
appear  with  great  rapidity  in  each  part.  This  rapidity  must 
not  be  too  great,  and,  where  there  is  a  tendency  in  this  di- 
rection, the  progress  of  the  etching  must  be  impeded  before 
it  has  acquired  a  sufficient  depth,  (which  requires  an  action 
of  a  few  minutes'  duration.)  If  in  these  preliminary  exper- 
iments it  be  found  that  this  tendency  prevails,  the  solution 
No.  2  has  to  be  modified  by  the  addition  of  a  portion  of  the 
saturated  solution  No.  1,  before  No.  2  can  be  employed  in 
the  etching  of  a  fresh  plate  ;  but  if,  on  the  contrary,  the 
engraving  fails  to  appear  after  the  lapse  of  a  minute,  or 
if  it  commences  but  proceeds  too  slowly,  it  is  a  sign  that  the 
liquid  No.  2  is  too  strong  or  too  near  its  saturation.  This 
deficiency  is  corrected  by  adding  a  little  water  before  it  is 
employed  for  a  second  plate.  In  making  this  correction  the 
operator  must  not  forget  that  a  small  quantity  of  water  often 
produces  a  great  difference  and  causes  the  etching  to  pro- 
ceed very  quickly.  As  soon  as  the  strength  of  No.  2  has 
been  appropriately  graduated,  which  in  general  requires 
three  or  four  experimental  trials,  it  may  afterward  be  em- 
ployed with  safety.  In  this  case  the  plate  is  flowed  as  before 
indicated,  and  the  operation  proceeds  until  all  the  details 
appear  and  present  a  satisfactory  aspect  to  the  eyes  of  the 
operator,  which  takes  place  generally  in  two  or  three  minutes, 
the  etching  liquid  being  kept  moving  over  the  surface  all  the 
time  by  a  camel's  hair  j)encil.  As  soon  as  it  appears  proba- 
ble that  the  engraving  will  not  be  any  better,  the  operation 
is  stopped,  by  wiping  off  the  fluid  with  a  pad  of  cotton  or 
of  wool  and  afterward  flowing  the  plate  with  a  sheet  of 
cold  water.  The  plate  is  then  wiped  with  a  clean  linen 
cloth,  and  afterward  rubbed  with  soft  Spanish  white  and 
water  in  order  to  remove  the  gelatine.  The  engraving  is 
now  complete. 

Another  method  by  the  same  author  is  the  following : 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER.  291 


When  the  plate  is  ready  for  etching  pour  upon  it  a  small 
quantity  of  No.  1,  the  saturated  solution.  This  may  be  left 
on  the  plate  for  a  minute  or  two.  No  apparent  effect  is  pro- 
duced by  this  operation,  but  it  acts  beneficially  by  hardening 
the  gelatine.  After  this  it  is  poured  off  and  a  sufficient 
quantity  of  No.  2  takes  its  place  and  produces  the  etching 
already  described,  which,  on  its  appearing  satisfactory,  re- 
quires nothing  more  to  be  done. 

But  it  frequently  happens  that  a  few  patches  of  the  engrav- 
ing, such  as  distant  mountains  or  vessels  in  a  landscape,  re- 
fuse to  appear,  and  as  without  these  the  engraving  would 
be  incomplete,  it  is  recommended  to  apply,  by  means  of  a 
camel's  hair  pencil,  a  little  of  No.  3  to  those  parts,  without 
pouring  off  No.  2.  This  simple  means  is  frequently  effective 
in  bringing  out  the  details  of  the  picture,  and  sometimes 
with  great  rapidity,  so  that  the  operator  has  to  be  very 
cautious  lest  this  fluid  might  corrode  parts  that  are  to  re- 
main white.  With  proper  skill  this  mode  of  strengthening 
certain  parts  will  be  found  of  great  advantage  in  bringing 
out  portions  which  probably  would  remain  invisible. 

Asphaltotype  of  JVicephore  Niepce. 

The  substance  used  to  produce  the  image  on  the  plate 
under  the  influence  of  light  is  asphaltum  or  the  bitumen  of 
Judea.  The  process  of  Nicephore  Niepce  has  undergone 
various  modifications  by  his  nephew  Niepce  de  Saint  Victor. 
The  solution  of  asphaltum  was  formerly  applied  by  means 
of  a  roller  covered  with  leather,  or  of  a  pad  of  cloth  or  leath- 
er ;  it  is  now  applied  like  collodion. 

Varnish  of  Niepce  de  Saint  Victor. 

Anhydrous  benzine,  90  parts. 

Essence  of  citron-peel,   10  parts. 

Pure  bitumen  of  Judea,  2  parts. 

In  order  to  render  the  benzine  more  anhydrous,  place  a 
quantity  of  freshly  prepared  chloride  of  calcium  in  the  vial 
which  contains  it,  and  shake  the  mixture  frequently.  In 
twenty-four  hours  it  may  be  used. 

Asphaltum  or  the  bitumen  above  mentioned  dissolves  very 
easily  in  benzine ;  it  is  necessary,  however,  to  shake  the 
mixture,  and  then  to  allow  it  to  settle  for  a  day  or  two,  after 
which  the  more  liquid  part  is  decanted  and  filtered  in  order 
to  remove  all  insoluble  particles.  The  varnish  is  then  very 
fluid,  and  produces  a  very  thin  film.  The  thinner  the  film, 
the  more  sensitive  it  is  to  light.     If  a  thicker  film  be 


292  PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 

required,  it  is  obtained  by  removing  the  stopper  of  the  vial 
for  a  while,  and  allowing  the  varnish  to  evaporate,  or  by- 
adding  three  or  four  parts  of  asphaltum  instead  of  two.  But  a 
thick  film  presents  more  resistance  to  the  etching  fluid,  and 
there  is  a  limit  to  its  application,  otherwise  the  half-tones  will 
be  entirely  wanting.  The  bottle  containing  the  varnish  must 
be  kept  filled  and  well  closed,  and  be  preserved  in  a  dark 
room,  if  it  is  to  be  kept  some  time.  It  is  better,  however, 
to  prepare  only  a  small  quantity  at  a  time  for  present  use. 

Preparation  of  the  Plate. 

Plates  of  steel,  copper,  zinc  or  of  glass  may  be  used  in 
this  process.  The  first  conditions,  naturally,  for  all  such 
operations  of  contact-printing,  are,  that  they  be  perfectly 
plane  and  well-polished.  Whether  direct  from  the  planing- 
machine  or  from  previous  use  where  it  has  failed  to  succeed, 
the  plate  of  steel,  for  instance,  is  cleaned  with  benzine  in 
order  to  remove  all  greasy  material,  then  rubbed  with  a  pad 
of  cotton  dipped  in  alcohol  ninety-five  per  cent  strong,  and 
very  fine  emery  powder.  By  this  means  the  steel  can  be 
polished  as  bright  as  a  daguerreotype  plate.  Copper  and  zinc 
plates  as  also  those  of  glass  are  polished  with  rotten-stone. 
Immediately  before  use  it  is  well  to  cover  the  steel,  etc.,  plate, 
with  a  coating  of  rotten-stone  and  alcohol,  allow  the  film  to  dry 
and  then  to  rub  it  off ;  afterward  use  the  broad  camel's  hair 
pencil,  as  in  the  wet  collodion  process,  in  order  to  remove 
all  particles  of  dust. 

Flowing  of  the  Varnish. 

This  operation  is  similar  to  many  others  already  briefly 
described.  Be  careful  not  to  shake  the  varnish  before  it  is 
poured  upon  the  plate,  otherwise  it  will  give  rise  to  an  in- 
finite number  of  small  bubbles  in  the  film.  Pour  the  varnish 
either  on  the  middle  or  the  upper  right-hand  corner  of  the 
plate,  as  you  would  collodion,  and  as  you  are  accustomed  to 
do  so  with  success ;  and  allow  the  excess  to  flow  off  at  the 
lower  right-hand  corner.  Invert  the  plate  and  let  it  lean 
against  the  wall  on  the  opposite  corner  to  that  from  which 
the  excess  was  poured  and  with  the  film  toward  the  wall. 
This  operation  may  be  performed  in  a  weak  diffused  light ; 
let  the  plate,  however,  dry  in  the  dark-room,  which  will 
take  place  very  rapidly,  and  use  it  as  soon  as  dry ;  for  its 
sensibility  is  now  the  greatest.  The  more  uniform  and  thin 
(to  a  certain  extent)  the  film  may  be,  the  greater  the  proba- 
bility of  a  successful  issue. 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


293 


Exposure  of  the  Plate. 
The  printing  operation  is  performed  in  the  printing  frame, 
only  a  transparent  positive  is  used  instead  of  a  negative.  A 
paper  print  maybe  substituted  for  the  glass  positive,  first  mak- 
ing the  paper  transparent  by  a  solution  of  wax  in  turpentine 
or  otherwise.  The  glass  positive  is  placed  upon  the  glass 
plate  of  the  printing  frame  ;  and  then  the  prepared  asphal- 
tum  plate  lies  upon  the  positive,  their  two  films  being  in 
contact.  In  this  the  frame  is  exposed  to  the  direct  rays  of 
the  sun  or  to  diffused  light.  The  time  of  exposure  will  sel- 
dom exceed  a  quarter  of  an  hour  in  the  sun  or  an  hour  in 
diffused  light ;  the  right  time  has  to  be  learned  by  experience. 

Development  of  the  Image. 
This  operation  consists  in  dissolving  the  parts  that  have 
not  been  acted  upon  by  light  and  thus  removing  them  and 
exposing  the  plate  beneath. 

Solvent. 

Rectified  oil  of  naphtha,  4  parts. 

Ordinary  benzine,  1  part. 

This  solvent  is  poured  upon  small  plates  in  the  same  way 
as  collodion,  or  the  developer,  etc. ;  but  when  the  plates  are 
large,  it  is  necessary  to  have  a  porcelain  or  glass  dish,  at  the 
bottom  and  the  left  end  of  which  the  plate  is  placed.  The 
solvent  is  poured  upon  the  inclined  right  end,  and  by 
elevating  this  end  the  liquid  flows  uniformly  over  the  whole 
plate.  This  operation  of  flowing  the  plate  must  be  perform- 
ed immediately  after  the  exposure,  whether  in  the  camera 
or  by  contact. 

If  the  action  of  the  light  has  been  too  long,  a  stronger 
solvent  is  needed  ;  the  strength  of  this  solution  is  increased 
either  by  increasing  the  quantity  of  the  benzine  or  diminish- 
ing that  of  the  naphtha.  If  the  whole  of  the  film  of  asphal- 
tum  is  dissolved  off,  the  action  of  the  light  has  not  been 
either  sufficiently  intense  or  prolonged  ;  if,  on  the  contrary, 
but  little  has  been  dissolved,  either  the  luminous  action  has 
been  too  long,  or  the  asphaltum  was  very  sensitive,  in  which 
case  the  image  is  always  foggy. 

If  the  asphaltum  peels  off  in  certain  parts  of  the  plate,  it 
is  an  evident  sign  the  plate  was  moist.  It  sometimes  happens, 
however,  that  when  the  film  is  too  thick,  the  same  incon- 
venience takes  place. 

The  solvent  may  be  used  several  times  in  succession, 
taking  care  to  filter  it  when  it  becomes  too  colored. 


294  PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 

'Washing  of  the  Plate, 
The  picture  in  general  appears  very  quickly,  so  that  the 
action  of  the  solvent  has  to  be  stopped  almost  immediately 
after  its  application.  If  the  exposure  has  been  too  long, 
the  solvent  action  of  the  varnish  is  not  so  rapid.  In  order 
to  prevent  all  further  action,  the  plate  is  plunged  into  a 
vessel  of  water  and  afterward  well  washed  beneath  the  tap 
until  every  trace  of  the  solvent  and  all  particles  of  dust  are 
removed.  The  plate  is  then  allowed  to  dry  spontaneously, 
or  is  dried  by  artificial  heat. 

Fumigation  of  the  Plates. 
The  film  of  asphaltum,  unfortunately,  is  not  quite  imper- 
meable to  the  action  of  the  etching  fluid  used  afterward. 
Various  means  have  been  resorted  to  so  as  to  obviate  this 
difficulty.  Wax  is  sometimes  added  in  small  proportions 
to  the  varnish  to  remedy  this  evil.  The  best  result  is  ob- 
tained by  subjecting  the  plates  after  development  to  the 
vapors  of  the  essence  of  lavender  or  spikenard.  For  this 
purpose  an  arrangement  is  required  similar  to  those  used 
for  iodizing  the  silver  plate  in  the  daguerreotype  process. 
At  the  bottom  of  this  vessel  a  small  porcelain  capsule  is 
placed  containing  the  pure  essential  oil  not  distilled  or  rec- 
tified, which  is  heated  from  below  by  means  of  a  spirit-lamp 
to  the  temperature  of  about  from  150°  Fahrenheit  to  170°  at 
the  most,  lest  the  oil  should  be  volatilized  in  too  large  a  quan- 
tity. In  the  first  place  let  the  fumigator  be  filled  with  vapor, 
then  introduce  the  plate  and  keep  it  there  for  two  or  three 
minutes.  The  same  essence  may  be  used  a  second  time, 
but  no  more. 

The  color  of  the  film  after  fumigation,  when  successful, 
must  be  the  same  as  before  it  has  been  acted  upon  by  the 
light,  bronzed  and  iridescent. 

The  plate  is  then  dried  by  exposing  it  a  moment  to  the 
air  before  the  etching  fluid  is  applied,  and  if  the  operation 
of  fumigation  has  been  properly  timed  and  conducted,  the 
film  has  become  quite  impermeable.  It  is  necessary  to 
guard  against  carrying  the  deposition  of  the  essential  oil 
too  far,  otherwise  the  acids  will  have  no  action  whatever 
upon  the  metallic  plate. 

Application  of  the  Aqua-Tinta  Granulation. 
This  operation  is  indispensable  for  plates  obtained  direct 
either  by  contact  or  in  the  camera  from  a  photograph,  a 
landscape  or  portrait,  etc. ;  if  the  plate  be  copied  from  an 


FEINTING  WITHOUT  THE  SALTS  OF  SILVER. 


295 


engraving,  it  is  not  necessary.  Without  this  expedient  the 
plate  will  not  retain  the  ink. 

The  grain  is  applied  in  the  following  manner :  Resin  re- 
duced to  an  impalpable  powder  is  placed  at  the  bottom  of 
a  box  made  for  this  purpose,  which,  by  means  of  a  pair  of 
bellows,  is  raised  into  a  cloud,  and  thus,  when  it  settles  on 
the  plate,  communicates  to  the  latter  the  granular  condi- 
tion denominated  aqua-tinta.  The  plate  is  then  heated, 
whereby  the  resin  becomes  melted  and  forms  a  sort  of  net- 
work over  the  whole  surface.  This  operation  gives  the 
shades  a  grain  more  or  less  fine,  (according  to  the  impal- 
pability of  the  powder,)  which  retains  the  printing  ink,  and 
thus  permits  numerous  impressions  to  be  taken  of  the  plate 
as  soon  as  the  varnish  and  the  resin  have  been  removed  by 
the  aid  of  fatty  bodies  and  essential  oils  or  benzine. 

Etching  of  the  Plate. 

It  would  be  useless  to  attempt  to  etch  a  plate  where  the 
conditions  are  not  appropriate.  The  film  must  have  a  bril- 
liant and  iridescent  appearance,  be  sufficiently  imperme- 
able to  the  acid  employed,  free  from  fogginess,  (that  is,  the 
metallic  plate  must  be  completely  denuded  in  the  deep 
shadows  and  partially  so  in  the  half-tones,)  and  the  aqua- 
tinta  grain  must  have  been  communicated  to  it.  This  being 
the  case,  proceed  as  follows  : 

Raise  a  border  of  mastic  all  round  the  edge  of  the  plate, 
and  varnish  those  parts  that  are  intended  to  be  quite  white 
in  the  print,  as  is  practised  in  ordinary  etching.  Next  pour 
upon  the  film  a  dilute  solution  of  nitric  acid,  beginning  with 
one  per  cent  of  acid,  and  strengthening  it  to  as  high  as 
twelve  per  cent,  according  to  the  resistance  of  the  varnish 
and  the  depth  of  etching  required.  The  etching  fluid  has 
to  be  changed,  without  increasing  the  per  centage  of  acid ; 
for  it  frequently  happens  that  the  plate  resists  the  action 
of  the  fluid  for  some  time,  and  especially  if  the  film  has 
been  fumigated  with  the  essential  oil  of  spikenard.  Very 
good  results  may  be  obtained  by  pouring  hot  water  over 
the  plate  before  the  acid  is  applied  ;  but  in  this  case  be  sure 
to  remove  every  bubble  of  water  from  the  interstices  by 
blowing  before  you  pour  on  the  etching  fluid. 

As  soon  as  the  etching  is  supposed  to  have  advanced  far 
enough,  all  further  action  is  suppressed  by  dipping  the  plate 
in  cold  water ;  this  must  be  done  in  time,  otherwise  the 
varnish  would  be  attacked  in  those  parts  that  ought  to  be 
preserved,  a  circumstance  that  sometimes  happens,  for  which 


296  PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 

unfortunately  no  definite  cause  can  be  ascribed.  To  obviate 
this  difficulty  a  saturated  solution  of  iodine  in  water  at  60° 
is  used  as  an  etching  fluid,  instead  of  the  aqua-fortis.  The 
fumigation  is  omitted ;  and  the  iodine  solution  is  poured 
upon  the  plate  and  kept  there  for  ten  or  fifteen  minutes,  until 
it  becomes  nearly  colorless ;  this  operation  is  repeated  two 
or  three  times,  until  the  etching  is  regarded  as  deep  enough 
or  nearly  so ;  it  is  then  terminated  by  employing  a  dilute  so- 
lution of  aqua-fortis,  which  completes  the  etching  without 
attacking  the  varnish. 

Copper  requires  a  much  stronger  etching  fluid  than  either 
steel  or  zinc,  and  iodine  can  not  be  used  in  this  case  ;  it  has 
therefore  been  recommended  to  etch  the  parts  by  galvanism. 

The  plates  in  general  require  touching  up  with  the  graver, 
especially  if  copied  from  photographs ;  whereas  distinct  pen 
and  ink  drawings  or  plans  or  maps  may  be  engraved  in  the 
way  prescribed,  without  requiring  the  aid  of  the  graver's 
tool. 

Etching  on  Glass. 
Etching  on  glass  is  performed,  when  the  plates  are  pre- 
pared, by  placing  them  with  the  film  downward  over  the 
fumes  of  hydrofluoric  acid.  For  this  purpose  a  box  is  con- 
structed of  lead,  of  the  size  and  shape  of  the  plate,  and 
about  two  inches  deep.  At  the  bottom  of  this  place  a  small 
saucer  of  lead  containing  pulverized  fluor  spar  and  sulphuric 
acid  intimately  mixed.  Cover  the  box  with  the  inverted  and 
prepared  plate  as  a  lid,  and  apply  heat  to  the  bottom  of  the 
leaden  box  by  means  of  a  spirit-lamp  ;  fumes  of  hydrofluoric 
acid  will  be  set  at  liberty,  and  will  corrode  those  parts  of  the 
glass  that  have  been  denuded  by  the  solvent. 

Negress  Process  for  Heliographic  Engraving. 
The  plate,  prepared  either  with  asphaltum  or  the  bichro- 
mate of  potassa  and  gelatine,  is  subjected  to  the  luminous 
impression  beneath  a  positive  instead  of  a  negative.  After 
exposure  and  washing,  the  plate  is  attached  to  the  negative 
pole  of  a  battery  and.  immersed  in  a  solution  of  gold  for 
electrolytic  purposes.  In  this  way  the  lights  of  the  design 
are  protected  with  a  film  of  gold,  the  middle  tones  are  par- 
tially covered,  and  the  blacks  only  just  sufficient  to  commu- 
nicate a  sort  of  reticulated  structure  which  forms  the  ne- 
cessary grain. 

Copies  for  the  Engraver  to  work  from. 
The  metallic  plate,  the  wood,  stone  or  glass  is  first  covered 
on  both  sides  with  a  varnish  quite  impermeable  to  the  action 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER.  297 


of  acids ;  it  is  then  flowed  on  the  prepared  surface  with 
iodized  or  bromo-iodized  collodion,  and  treated  in  every  re- 
spect the  same  as  a  glass  plate  for  the  reception  of  an  ambro- 
type ;  that  is,  it  is  sensitized  in  the  bath  of  nitrate  of  silver, 
exposed  in  the  camera,  or  by  contact  with  an  albumen,  etc., 
print  on  glass  to  the  view,  etc.,  developed,  fixed,  washed 
and  dried.  Finally,  the  surface  of  the  picture,  thus  obtain- 
ed, is  covered  with  a  solution  of  dextrine  to  preserve  it  from 
injury.  The  plate,  etc.,  is  now  ready  for  the  draughtsman, 
and  when  prepared  by  him  by  means  of  a  fine-pointed  style, 
it  is  submitted  to  the  etching  fluid,  as  before  directed. 

Photo-lithography  and  Photo-zincography. 

These  branches  have  been  brought  to  a  high  degree  of 
success  within  the  last  two  or  three  years.  They  are  not 
yet  quite  perfect ;  the  want  of  perfection  consists  in  the  in- 
ability to  obtain  easily  and  uniformly  the  middle  tones.  Draw- 
ings in  pen  and  ink,  maps,  plans,  pages  of  letter  press,  etc., 
in  which  there  is  no  intermediate  tones  between  the  lights 
and  shades,  are  executed  to  any  amount  of  reduplication  by 
the  photo-lithographic  process,  and  very  successfully ;  but 
landscape  scenery,  architecture  and  portraiture,  where  there 
is  a  regular  blending  of  light  into  shade,  can  not  always  and 
at  will  be  reproduced  satisfactorily  by  any  of  the  known 
processes  of  photo-lithography  or  photo-zincography,  al- 
though it  must  be  confessed  that  the  specimens  published  in 
the  work  on  Photo-zincography  by  Colonel  Sir  Henry  James 
indisputably  prove  the  possibility  of  the  accomplishment  of 
this  desideratum. 

The  various  processes  practised  in  this  department  of  pho- 
tography depend  upon  the  properties  of  asphaltum,  the  per- 
salts  of  iron,  and  of  chrome  already  frequently  alluded  to  ; 
and  the  object  to  be  attained  consists  either  in  preparing 
surfaces  where  the  shades  are  etched  out  as  in  the  copper- 
plate, or  in  relief,  as  in  common  type. 

In  some  processes  the  designs  are  taken  directly  upon 
stone  or  zinc;  in  others  on  prepared  paper,  and  afterward 
transferred  to  stone  or  zinc.  By  the  latter  the  picture  is  ob- 
tained in  a  direct  position  ;  whereas  by  the  former,  without 
previous  arrangement,  the  image  is  inverted. 

Asphalto-photolithographic  Process. 
This  process  was  originally  employed  by  Uicephore  Niepce 
in  the  production  of  heliographic  engravings.    The  first  at- 
tempts in  photo-lithography  were  made  at  the  suggestion  of 
13* 


298  PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


Barreswil,  in  connection  with  Lemercier,  a  lithographer,  and 
Lerebours,  an  optician.  Davanne,  too,  co-editor  with  Bar- 
reswil, of  the  Chimie  Pliotographiqiie,  assisted  in  the  pre- 
paration of  the  specimens  published  as  early  as  1853. 

The  properties  of  asphaltum  dissolved  in  ether  or  in  es- 
sential oil,  are  the  following  : 

First.  It  is  sensitive  to  light,  and  becomes  changed  in  pro- 
portion to  the  intensity,  whereby  parts,  not  acted  upon  by 
the  luminous  impression,  can  be  removed  by  a  subsequent 
operation  of  washing  with  a  solvent. 

Second.  It  is  sufficiently  adhesive  to  the  stone  and  im- 
permeable to  the  etching  liquids  to  prevent  the  latter  from 
acting  upon  the  stone,  excepting  on  the  parts  denuded  by  the 
solvent. 

Third.  The  parts  of  asphaltum  left  on  the  stone  have  an 
attraction  for  the  greasy  ink  used  in  photo-lithography. 

Now  these  are  the  properties  required  in  photo-litho- 
graphy : 

The  stone  is  first  prepared  as  for  lithographic  purposes,  and 
then  placed  on  a  leveling  stand  and  made  perfectly  hori- 
zontal. Next  take  a  quantity  of  bitumen,  reduce  it  to  a 
powder  and  dissolve  it  in  ether ;  filter  as  much  of  the  solu- 
tion as  may  be  required  to  flow  the  stone.  Whilst  flowing 
the  stone  with  this  preparation  be  very  careful  to  avoid  agi- 
tating the  air  so  as  to  set  the  dust  in  motion,  or  produce  un- 
dulations in  the  film.  The  excess  of  bitumen  may  be  allowed 
to  flow  off  on  the  sides  and  corners ;  and  where  there  is  a 
tendency  of  the  fluid  to  become  stagnant  or  to  flow  back 
again  upon  the  stone,  this  is  prevented  by  the  application  of 
a  glass  rod  to  guide  the  superfluous  fluid  over  the  sides. 
The  object  is  to  obtain  a  thin,  uniform  film,  which  beneath  a 
magnifying  glass  presents  a  reticulated  appearance  all  over 
the  stone,  communicating  to  it  what  is  denominated  by  en- 
gravers a  grain.  The  quantity  of  asphaltum  in  ether  re- 
quired to  produce  such  a  thin  and  uniform  film  has  to  be 
ascertained  by  practice. 

As  soon  as  the  asphaltum  is  dry,  a  negative  is  placed  on  its 
surface,  (the  two  films  being  in  juxtaposition,)  and  is  held 
down  in  contact  by  pressure  on  the  sides  and  corners  by  means 
of  a  pressure-frame.  Any  negative  may  be  used.  The  stone 
is  now  exposed  to  the  light  of  the  sun  for  a  time,  which  has 
to  be  learned  by  experience.  This  operation  being  con- 
cluded, the  stone  is  taken  into  a  room  feebly  lighted,  the 
negative  is  removed  and  the  surface  containing  the  latent 
image  is  washed  with  ether.    The  parts,  on  which  the  light 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER.  299 


has  acted,  have  become  insoluble  ;  these,  therefore,  are  not 
disturbed  by  the  solvent ;  whereas  all  the  rest  of  the  bitu- 
minous film  that  has  been  protected  by  the  shades  of  the 
negative,  is  dissolved  and  washed  off.  If  the  time  of  expo- 
sure has  been  too  short,  the  image  is  destitute  of  all  middle 
tones  ;  it  is  mere  black  and  white ;  if,  on  the  contrary,  the 
exposure  has  been  too  long,  the  picture  is  foggy,  that  is,  the 
fine  lines  have  become  heavy  and  the  stone  imperfectly  de- 
nuded in  the  lights.  In  order  to  be  successful,  the  surface 
must  be  well  washed  Avith  ether,  otherwise  spots  will  arise 
that  can  not  afterward  be  removed. 

The  film  is  then  dried,  and  if  the  image  thus  formed  is  satis- 
factory, the  stone  is  then  treated  in  the  same  manner  as  a 
drawing  with  lithographic  crayons  ;  that  is,  it  is  first  flowed 
with  a  weak  acid  solution  containing  a  little  gum,  so  as  to 
preserve  the  whites  and  give  more  transparency  to  the  pic- 
ture ;  it  is  then  washed  in  several  waters,  and  if  need  be,  in  oil 
of  turpentine  ;  finally  it  is  inked  with  lithographic  ink.  If  all 
succeeds  well,  the  image  will  take  the  ink  with  facility  as  soon 
as  the  roller  is  passed  over  it,  and  will  require  no  touching 
up.  Prints  are  obtained  from  stones,  prepared  in  the  man- 
ner above  described,  as  with  any  other  lithographic  stone ; 
they  improve  gradually  after  a  number  of  impressions  have 
been  taken.  The  authors,  whose  process  I  have  copied,  as- 
sert that  they  have  prepared  a  number  of  stones  by  this  pro- 
cess, that  have  given  great  satisfaction  and  have  not  been 
worn  out  quicker  than  any  ordinary  lithographic  impression. 

Bicliromo-photo-lithograpliic  Processes  of  jPoitevin. 

The  mixture  proposed  by  Talbot  of  bichromate  of  potassa 
and  organic  matter,  such  as  gelatine,  albumen,  gum,  etc.,  is 
used  by  Poitevin  in  the  processes  about  to  be  described. 

An  ordinary  lithographic  stone  is  covered  with  a  solution 
of  albumen  and  bichromate  of  potassa,  and  allowed  to  dry 
spontaneously.  It  is  then  exposed  to  the  light  of  the  sun 
beneath  an  albumen,  tannin,  etc.,  negative,  by  which  the  parts 
to  which  the  light  has  not  been  able  to  penetrate  through  the 
opaque  shades  of  the  negative,  are  preserved  in  their  natural 
and  soluble  condition,  while  the  parts  impressed  by  the  light 
have  become  insoluble.  Thus  modified,  the  latter  parts  repel 
water,  as  if  the  light  had  produced  some  greasy  substance 
in  the  film.  In  this  condition  these  parts  easily  adhere  to 
ordinary  lithograpic  ink,  whilst  there  is  no  adherence  be- 
tween the  ink  and  those  parts  that  have  undergone  no  actinic 
impression.    A  roller  charged  with  such  ink  is  then  passed 


.300 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


over  the  stone ;  and  the  image  is  made  manifest  by  the  ad- 
herence of  the  ink  to  the  parts  impressed  and  in  accordance 
with  the  intensity  of  the  impression.  The  excess  of  ink  is 
removed  with  a  wet  sponge.  The  stone  is  then  covered  with 
a  weak  acid  which  acts  upon  the  parts  not  imbued  with  ink, 
and  thus  presents  the  image  in  relief,  which  is  treated  after- 
ward like  any  other  ordinary  drawing  on  stone  with  litho- 
graphic crayons. 

Photo-typographic  Process  of  Poitevin. 
Poitevin  has  also  availed  himself  of  a  peculiarity,  which 
gelatine  in  connection  with  bichromate  of  potassa  possesses, 
of  swelling  when  exposed  to  cold  water  and  before  it  has 
been  impressed  by  light.  His  mode  of  proceeding  is  as 
follows  : 

A  plate  of  glass  is  flowed  with  an  even  film  of  a  solution 
of  gelatine,  which  is  allowed  to  dry  spontaneously.  The 
plate  is  then  immersed  in  a  concentrated  solution  of  bichro- 
mate of  potassa  ;  and  when  the  film  has  become  completely 
permeated  with  the  salt,  the  plate  is  quickly  washed  in  order 
to  remove  all  excess  of  the  solution,  and  is  put  away  in  the 
dark-room  to  dry.  The  plate  is  then  ready  for  exposure 
beneath  a  negative,  which  must  be  very  clear,  transpar- 
ent, well-defined  and  vigorous.  After  exposure  it  is  im- 
mersed in  cold  water,  by  which  the  parts  that  have  been 
protected  beneath  the  dark  shades  of  the  negative,  swell.  In 
this  condition  the  plate  is  moulded  in  plaster.  This  mould 
is  afterward  submitted  to  the  electrolytic  action  of  a  gal- 
vanic battery,  from  which  a  metallic  matrix  may  be  obtained 
for  printing  from  by  the  typographic  press. 

The  processes  above  described,  whatever  the  success  iu 
manipulation,  are  defective  in  one  essential  point:  the  pic- 
tures are  laterally  inverted.  It  is  true  that  negatives  may 
be  obtained  by  copying  in  a  condition  to  produce  the  proper 
effect. 

Photo-lithographic  Process  of  Newton. 

A  lithographic  stone  or  a  plate  is  covered  with  a  solution 
of  one  quart  of  water,  four  ounces  of  gum-arabic,  one  hun- 
dred and  sixty  grains  of  sugar,  and  a  certain  quantity  of  bi- 
chromate of  potassa.  The  stone  is  then  put  away  to  dry  in 
the  dark-room.  It  is  next  exposed  either  in  the  camera  or 
beneath  a  transparent  positive.  The  gum  becomes  almost 
insoluble  by  the  action  of  the  light.  The  stone  is  then  washed 
with  a  solution  of  soap,  which  removes  the  parts  that  have 
not  been  acted  upon  by  light,  while  the  soap  is  decomposed 


PRINTING  "WITHOUT  THE  SALTS  OF  SILVER. 


301 


in  those  parts  where  the  luminous  impression  has  been  made, 
"  the  action  of  the  soap  being  inversely  proportional  to  the 
intensity  of  the  light."  The  stone  thus  prepared  is  washed 
with  water,  and  when  it  is  dry  it  is  covered  by  means  of  a 
roller  with  a  layer  of  printer's  ink,  which,  combining  with 
the  soap,  adds  new  body  to  the  print.  When  it  is  desired 
to  obtain  gradations  of  light  and  shade,  the  stone  is  submitted 
to  the  graining  process  above  described;  but  this  is  not  ne- 
cessary where  blacks  and  whites  alone  are  required. 

It  is  difficult  to  observe  any  fundamental  difference  be- 
tween this  process  of  Newton  and  the  preceding  one  of  Poi- 
tevin ;  it  is  apparently  a  mere  copy.  The  remaining  pro- 
cesses to  be  described  are  the  most  important  and  successful ; 
they  are  founded  upon  a  discovery  of  Asser  of  Amsterdam, 
the  transfer-process,  although  Sutton  had  remarked  that 
printer's  ink,  put  on  gelatine  paper,  would  come  away,  if 
soaked  in  water,  leaving  the  paper  quite  clean. 

This  process  consists  in  first  obtaining  a  picture  on  paper 
prepared  with  bichromate  of  potassa  and  organic  matter, 
and  then  in  transferring  this  direct  picture  on  stone  or  zinc, 
which,  being  laterally  inverted,  yields  a  direct  print  in  the 
press.  The  process  has  been  much  improved  in  the  manipu- 
lations both  by  Osborne  in  Australia,  as  well  as  by  Captain 
Scott  and  Colonel  Sir  Henry  James,  in  the  Ordnance  Office, 
Southampton.  Osborne,  it  appears,  made  his  discoveries  and 
improvements  independently  of  Asser's  publication,  and  of 
those  from  the  Government  office  in  Southampton.  These 
processes  being  then  essentially  the  same,  it  will  not  be  ne- 
cessary to  describe  more  than  one  in  this  work.  Colonel  Sir 
H.  James  has  just  published  a  new  edition  of  his  Photo-zin- 
cography, accompanied  with  very  neat  specimens  of  prints 
that  can  be  obtained  directly  from  photographic  negatives 
by  this  process. 

Photo-zincography  by  Colonel  Sir  II.  James,  P.JE.  /  and 
Photo-lithography  by  Mr.  Osborne. 
The  negatives  in  this  sort  of  work  require  above  all  things 
to  be  very  transparent,  without  the  slightest  fogginess  in 
the  transparent  parts ;  the  opaque  parts,  on  the  contrary, 
must  be  exceedingly  dense.  Such  negatives  can  be  obtained 
only  by  redevelopment  or  intensifying.  The  exposure  of 
the  collodion  plate  to  light  is  not  quite  so  long  as  for  an 
ordinary  negative,  nor  is  the  development  carried  on  to  the 
same  extent  in  the  first  instance  as  for  a  negative ;  it  is  bet- 
ter to  stop  the  action  of  the  iron  solution  as  soon  as  the  pic- 


302 


PRINTING  WITHOUT  THE  SALTS  OF  SILYEE, 


ture  has  appeared  in  full  brilliancy  as  a  positive,  and  then  to 
intensify  afterward.  For  copying  engravings,  pen  and  ink 
drawings,  maps,  plans,  etc.,  where  the  delineations  are  purely 
black  and  white,  this  mode  of  preparing  the  negatives  is  cer- 
tainly to  be  recommended.  Where  there  is  a  gradation  of 
tone,  the  time  of  exposure  and  of  development  must  be  in- 
creased beyond  that  of  a  positive  or  ambrotype,  but  yet  not 
to  the  same  extent  as  for  a  negative. 

To  intensify  the  first  sort  of  negative,  that  is,  the  one  for 
copying  engravings,  etc.,  proceed  as  follows,  as  soon  as  it  has 
been  developed  and  fixed  and  is  perfectly  clear  in  the  trans- 
parent parts : 

While  the  plate  is  still  moist,  flow  it  with  a  part  of  the 
following  solution : 

Pyrogallic  acid,  3  grains. 

Glacial  acetic  acid,     .  48  minims. 


After  moving  the  solution  backward  and  forward  for  a 
minute  or  so,  pour  it  off  into  a  wine-glass,  and  add  to  it 
about  six  drops  of  a  solution  of  nitrate  of  silver  thirty  per 
cent  strong,  if  the  plate  is  stereoscopic  size,  and  so  on,  ac- 
cording to  the  size ;  shake  the  mixture  well  and  then  flow 
the  plate  with  it,  and  keep  it  in  motion,  and  watch  the  prog- 
ress of  blackening  by  the  light  transmitted  from  below,  as 
before  directed  and  described  in  the  article  on  the  negative 
collodion  plate.  It  may  be  necessary  to  add  more  silver,  or 
even  to  repeat  the  close  of  the  intensifier,  sometimes  two  or 
three  times ;  this,  however,  is  a  rare  occurrence  if  the  time 
of  exposure  has  been  right.  When  the  shades  are  quite 
opaque,  the  operation  is  so  far  complete.  Wash  thoroughly 
and  examine  the  plate  in  diffused  light.  If  the  lines  have 
become  somewhat  thickened,  or  the  transparent  parts  slightly 
fogged,  these  evils  must  be  remedied  by  Osborne's  clarify- 
ing process. 

Dissolve  iodine  in  a  solution  of  iodide  of  potassium  to 
saturation  ;  of  this  solution  take  ten  or  twelve  drops  to  four 
drachms  of  water,  (for  a  stereoscopic  plate,)  and  pour  the  so- 
lution on  the  moist  plate,  and  keep  it  in  motion  until  the  sur- 
face of  the  negative  assumes  a  uniform  film  of  a  cream  color. 
Wash  the  plate  and  flow  it  with  a  very  dilute  solution  of 
cyanide  of  potassium.  This  will  remove  the  iodide  of  silver 
and  diminish  the  thickness  of  the  lines  and  the  fogged  ap- 
pearance of  the  transparent  parts. 

Sir  H.  James  intensifies  with  bichloride  of  mercury,  by 


Alcohol,  .  . 
Distilled  water, 


36  minims. 
2  ounces. 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


303 


immersing  the  well- washed  plate  in  a  weak  solution  of  this 
salt ;  as  soon  as  the  surface  is  whitened  by  the  action  of 
the  mercurial  salt,  it  is  washed  again,  and  a  dilute  solution 
of  sulphide  of  ammonium  is  poured  over  it,  which  changes 
the  color  to  a  brown-yellow.  If  the  negative  is  allowed  to 
dry,  the  bichloride  is  used,  there  will  be  less  danger  of  fill- 
ing up  the  lines  ;  but  the  edges  of  the  film  must  be  varnished 
first,  to  prevent  it  from  slipping  off  when  it  is  washed. 

After  the  negative  has  been  intensified  and  is  dry,  it  is 
varnished,  and  is  then  ready  for  use. 

The  following  are  the  formulae  for  the  various  solutions 
recommended  by  Sir  H.  James : 

For  Cleaning  the  Glass  Plate. 

Alcohol,  1  ounce. 

Ammonia,  J  drachm. 

Water,  8  ounces. 

Tripoli  powder,  sufficient  to  give  it  the  consistence  of  cream. 

Collodion. 

Pyroxyline,  80  grains. 

Iodide  of  cadmium,  15  grains. 

Iodide  of  potassium,    ,  75  grains. 

Alcohol,  sp.  gr.,  .812,  10  ounces. 

Ether,  sp.  gr.,  .725,   10  ounces. 

Nitrate  of  Silver  Bath. 

Nitrate  of  silver  recrystallized  or  fused,  .    .    1  ounce. 
Water,  14  ounces. 

Dissolve  and  filter,  then  coat  a  plate  with  iodized  collo- 
dion, and  immerse  for  twelve  hours  in  order  to  saturate  the 
bath  with  iodide.  If,  on  exposing  the  plate,  there  should  be 
any  sign  of  fogging,  add  dilute  nitric  acid,  (one  of  acid  to 
ten  of  water,)  drop  by  drop,  until  a  clear  picture  is  obtain- 
ed. If  at  any  time  the  bath  should  be  too  acid,  it  can  be 
neutralized  by  adding  a  little  oxide  of  silver. 

Developing  Solutions. 


Iron. 

Protosulphate  of  iron,  .    1  ounce. 
Glacial  acetic  acid,    .    .    6  drachms. 

Alcohol,  6  drachms. 

Water,  distilled,  ...  20  ounces. 


Pyrogallic  Acid. 
Pyrogallic  acid,  ...    30  grains. 
Glacial  acetic  acid,    .    .    1  ounce. 

Alcohol,  6  drachms. 

Water,  distilled,     .    .    20  ounces. 


Fixing  Solution. 

Cyanide  of  potassium,  15  grains. 

Water,  1  ounce. 


804 


PRINTING  WITHOUT  THE  SALTS  OP  SILVER. 


Quality  of  the  Paper  used  in  the  Transfer  Process. 

The  paper  suitable  for  this  purpose  must  be  hard,  thin, 
and  tough,  of  even  texture,  free  from  wooliness,  and  but 
slightly  sized.  Paper  made  from  linen  is  the  best,  such  as 
that  used  for  bank  post  paper.  If  there  is  too  much  size  in 
the  structure,  it  can  be  remedied  by  steeping  the  paper  in 
hot  water  a  short  time  before  coating  it  with  the  solution. 

Coating  of  the  Paper  toith  the  Sensitive  Solution. 
This  solution  must  be  quite  fluid  at  the  temperature  of  100°. 

Dissolve   \  Bichromate  of  potassa  .    .    -  jounces.) 

(  Hot  water,  ram  or  distilled,)    ...    10   ounces.  ) 

Dissolve   \  Gelatine>  (the  finest,)  3   ounces.  }  N  9 

(  Hot  water,  (rain,  etc.,)  40   ounces.  \ 

Mix  the  two  solutions  and. filter  while  warm.  When  about 
to  be  used  let  it  be  poured  into  a  large  flat  dish,  and  main- 
tained at  a  temperature  of  100°  by  placing  this  dish  in  an- 
other containing  warm  water. 

Float  the  paper  on  this  solution  with  the  right  side  down- 
ward for  three  minutes,  taking  care  to  break  up  all  bubbles  ; 
the  operation  is  performed  in  the  dark-room.  Drain  the 
paper  and  hang  it  up  to  dry  in  the  manner  already  described 
in  the  positive  printing  process.  When  dry,  the  paper  is 
floated  a  second  time  and  hung  up  to  dry  by  an  opposite 
corner. 

The  surface  is  afterward  smoothed  by  passing  it  through 
a  copperplate  press  on  a  hot  steel  plate — the  rolling  press 
with  a  flat  plate  is  also  quite  suitable  for  this  purpose. 

Exposure  under  the  Negative. 
The  amount  of  exposure  is  regulated  by  the  appearance 
of  the  print.  When  the  lines  appear  distinctly  marked,  and 
of  a  dark  brownish-green,  the  operation  is  complete.  The 
time  will  vary  with  each  negative,  and  with  the  light,  from 
one  minute  in  the  sun  to  twenty  minutes  in  dull  weather.  If 
the  printing  is  incomplete,  the  lines  will  break  beneath  the 
sponge  in  the  washing ;  and  where  the  exposure  has  been 
too  long,  the  ink  (to  be  afterward  applied)  will  adhere  to  the 
ground  of  the  print. 

The  Inking  of  the  Bichromate  Print. 
Formula  for  the  Ink. 

Chalk  lithographic  ink,  2  pounds. 

Middle  linseed  oil  varnish,   .1  pound. 

Burgundy  pitch,  4  ounces. 

Palm  oil,  2  ounces. 

White  wax,  2  ounces. 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER.  305 


Melt  the  three  latter  in  an  iron  pot  until  they  begin  to 
burn,  stirring  the  ingredients  all  the  time ;  finally,  add  the 
varnish  and  the  ink,  and  mix  intimately. 

When  about  to  use  this  ink,  the  necessary  quantity  is 
melted  with  a  proportion  of  turpentine,  so  as  to  reduce  it, 
when  cold,  to  the  consistence  of  thick  molasses.  A  small 
quantity  is  laid  on  the  printing  roller,  which  is  then  worked 
on  a  stone  in  the  usual  manner,  till  the  coating  is  perfectly 
even. 

The  closer  and  finer  the  lines  of  the  print  are,  the  thinner 
should  be  the  coating  of  ink. 

A  zinc  plate  is  inked  writh  the  printing  roller,  and  the  bi- 
chromate print  is  laid  face  downward  on  it,  and  passed 
through  a  lithographic  press ;  by  this  means  it  receives  a 
very  even  coating  of  ink. 

The  Cleaning  of  the  Surface  of  the  Print. 

After  the  operation  of  inking  the  print  is  floated  on  water 
at  90°,  back  downward,  for  five  minutes  ;  it  is  then  placed 
face  upward  on  a  porcelain  or  marble  slab,  and  the  surface 
is  gently  rubbed  with  a  new  soft  sponge  dipped  in  gum- 
water.  If  all  the  previous  operations  have  been  well  per- 
formed, the  ink  will  readily  leave  the  ground  of  the  print 
remaining  on  the  lines. 

The  less  friction  is  used  the  better;  if  the  ink  does -not 
easily  leave  the  paper  where  it  ought  to  do  so,  the  print 
must  be  floated  once  more  on  the  warm  water,  face  down- 
ward, for  a  few  minutes. 

As  soon  as  the  ground  of  the  print  is  quite  cleared  of  ink, 
and  the  whites  appear  in  the  closest  parts  where  they  show 
on  the  original,  the  paper  is  thoroughly  washed  in  tepid 
water  to  remove  all  the  gum  from  the  surface,  so  that  no 
trace  remains.  It  is  then  dried  and  is  ready  for  transferring 
to  zinc  or  stone. 

Transference  of  the  Print  to  Zinc  or  Stone. 
The  plates  of  zinc  are  first  scraped  until  all  inequalities 
are  removed.  A  piece  of  a  saw-blade  makes  a  good  scraper. 
Let  it  be  four  inches  long  and  three  wide,  in  the  form  of  a 
rectangle.  Grind  the  long  sides  quite  flat  on  a  grindstone, 
so  that  these  surfaces  present  two  sharp  edges  for  scraping. 
Use  the  scraper  as  in  veneering.  When  the  surface  of  the 
zinc  is  thus  made  free  from  blisters,  scratches,  etc.,  grind  it 
down  flat  with  a  pumice-stone,  and  smooth  it  with  snake- 
stone.  Finally  it  is  grained  with  a  disk  of  zinc  four  inches 
in  diameter,  half  an  inch  thick,  and  fixed  to  a  handle,  by 


306 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER. 


rubbing  the  disk  with  a  circular  movement  over  the  surface 
with  fine  sand  and  water.  The  sand  is  passed  through  a 
wire  sieve  containing  from  eighty  to  one  hundred  and  twenty 
meshes  in  a  square  inch.  As  soon  as  this  operation  is  com- 
plete, the  plate  is  thoroughly  washed  and  dried,  and  then 
used  immediately. 

Old  plates  are  first  cleaned  with  turpentine,  then  with  an 
alkali,  and  finally  with  a  mixture  of  equal  parts  of  sulphuric 
and  hydrochloric  acid  to  twelve  parts  of  water.  The  grain- 
ing, too,  is  repeated. 

The  bichromate  print  is  first  moistened  between  sheets  of 
damp  paper  for  a  few  minutes,  then  placed  face  downward 
on  the  zinc  plate,  with  two  or  three  sheets  of  paper  over  it, 
and  passed  through  the  press. 

If  the  transfer  print  is  not  more  than  three  or  four  days 
old,  it  will  be  sufficient  to  pass  it  through  once ;  but  an  old 
print,  on  which  the  print  has  had  time  to  harden,  will  re- 
quire to  pass  through  the  press  two  or  three  times. 

The  sheets  of  paper  covering  the  transfer  are  then  re- 
moved, and  the  latter  is  damped  with  a  wet  sponge  for  two 
or  three  minutes  ;  this  causes  the  gelatine  in  the  lines  to 
swell,  and  makes  the  ink  leave  them  more  readily. 

The  print  is  then  pulled  carefully  from  the  plate  ;  and  near- 
ly the  whole  of  the  ink  should  remain  on  the  zinc. 


Bruise  the  galls  in  a  mortar  and  steep  them  in  the  wate'r 
for  twenty-four  hours ;  after  which  the  mixture  is  made  to 
boil  over  the  fire,  and  then  filtered. 

(  Gum  water  of  the  consistence  of  cream,    .    3  quarts. 


The  phosphoric  acid  is  prepared  in  the  following  manner : 
Take  a  bottle,  three  quarters  full  when  holding  a  pint  of 
water,  and  insert  sticks  of  phosphorus  in  the  water,  so  that 
parts  of  them  are  exposed  to  the  air  above  the  fluid.  An 
incision  is  cut  in  the  cork  to  let  in  air.  The  phosphorus 
thus  becomes  oxidized,  and  the  phosphoric  acid  is  dissolved 
by  the  water  below.  In  a  few  days  the  solution  is  suffi- 
ciently strong  for  use. 

The  etching  liquid  is  poured  on  the  plate,  and  spread  over 


Etching  of  the  Zinc. 
The  etching  liquid  is  prepared  as  follows : 


4  ounces. 
3  quarts. 


1  quart. 
3  ounces. 


PRINTING  WITHOUT  THE  SALTS  OF  SILVER.  307 


the  surface  with  a  sponge  or  camel's  hair  brush.  For  fine 
work  twenty  seconds  will  be  sufficient ;  whereas  strong  lines 
would  bear  the  action  of  a  minute  without  injury.  The 
etching  solution  is  next  removed  entirely  with  a  cloth  dipped 
in  water. 

Finally,  the  transfer  ink  is  cleared  from  the  plate  with  tur- 
pentine, or  if  the  design  is  weak,  with  turpentine  mixed  with 
olive  oil  and  gum-water.  The  plate  is  then  rolled  up  with 
printing  ink,  the  roller  being  very  thinly  and  evenly  coated 
with  it.  Impressions  can  then  be  printed  in  the  usual  man- 
ner; fifteen  hundred  is  not  an  unusual  number  for  the  plate 
to  stand  without  sensible  deterioration. 

The  bichromate  print  can  be  transferred  to  a  lithographic 
stone  in  a  similar  manner. 

When  the  subject  admits  of  it,  paper,  enameled  with  zinc- 
white,  should  be  used,  as  the  impressions  produced  are  more 
perfect. 

Formula  for  Zinc  Enamel. 

j  j  Russian  glue,  4  ounces. 

(  Water,  3  quarts. 

Soak  for  several  hours,  and  then  dissolve  by  heat : 

No.  2.  -{  Zinc  white,  (oxide  of  zinc,)     ....    1^  pounds. 

Grind  with  water  on  a  slab,  mix  gradually  with  the  solu- 
tion of  glue,  and  pass  through  a  hair-sieve. 

This  enamel  is  communicated  to  the  paper  with  a  broad 
brush,  and  the  streaks  are  obliterated  with  a  flat  camel's 
hair  pencil.  A  second  coating  is  applied  in  a  similar  man- 
ner, when  the  paper  is  hung  up  to  dry. 

Sir  H.  James  remarks  that,  since  the  publication  of  the 
first  edition  of  the  process  above  copied  from  his  work,  he 
has  discovered  that  the  paper  coated  with  the  bichromate  of 
potassa  and  gelatine,  after  exposure  in  the  printing  frame  as 
already  described,  can  be  made  to  produce  transfers  with 
half  tone  or  gradation  of  shade  by  using  the  following  com- 
position for  the  ink,  and  washing  with  a  soft  sponge  moist- 
ened with  tepid  water  without  gum,  and  by  using  a  very 
gentle  hand  in  the  manipulation. 

Formida  for  Transfer  Ink. 

Lithographic  printing  ink,   8  ounces. 

Middle  lithographic  varnish,  ......  4  ounces. 

Burgundy  pitch,   4  ounces. 

Palm  oil,   4  drachms. 

White  wax,   4  drachms. 


308  PKINTESTG  WITHOUT  THE  SALTS  OF  SILVER. 


Photo-papyrography  by  Colonel  Sir  II.  James,  R.JE. 

This  is  a  method  of  obtaining  a  single  copy,  or  a  copy 
or  two  of  some  manuscript,  plan  or  document,  etc.,  on 
paper,  without  incurring  all  the  trouble  of  preparing  either 
a  stone  or  a  plate  of  zinc.  For  this  purpose  a  nega- 
tive has  to  be  prepared,  by  copying  according  to  plans  al- 
ready minutely  described,  in  which  the  parts  are  not  later- 
ally inverted.  This  can  be  effected  too  by  simply  presenting 
the  glass  surface  (not  the  collodion  surface)  to  the  view,  etc., 
in  the  camera. 

With  such  a  negative  and  with  paper  already  prepared 
with  the  film  of  gelatine  and  bichromate  of  potassa,  a  posi- 
tive picture  can  be  obtained  in  carbon  ink,  laterally  inverted. 
The  image  is  brought  out  precisely  as  described  in  the  pro- 
cess of  photo-zincography.  It  is  then  placed  face  downward 
on  a  sheet  of  paper  and  passed  through  a  lithographic  press. 
A  sharp  and  clean  impression  is  thus  obtained. 

Colonel  Sir  H.  James  prepares  negatives  on  paper  covered 
or  flowed  with  the  wet  collodion  process.  The  sensitive- 
ness is  superior  to  that  of  collodion  on  glass,  and  the  nega- 
tives, when  waxed,  give  excellent  results. 

On  the  production  of  Photographs,  etc.,  on  Glass  in  Enamel 
Colors  by  Joubert. 
A  piece  of  crown  or  plate  glass  is  selected  for  receiving 
the  photograph;  this  glass  must  be  as  free  as  possible  from 
all  flaws.  It  is  cleaned  as  usual,  and  flowed  with  the  fol- 
lowing solution: 

Saturated  solution  of  bichromate  of  ammonia,    .    5  drachms. 

Honey,  3  drachms. 

Albumen,  3  drachms. 

Distilled  water,  20  to  30  drachms. 

Mix  intimately  and  filter  in  the  dark-room.  As  soon  as 
the  plate  is  dry  by  means  of  artificial  heat  from  a  stove  or 
otherwise,  it  is  placed  in  contact  with  a  transparent  positive 
in  the  printing-frame.  An  exposure  of  a  few  seconds  to  the 
sun  will  show,  on  removal  from  the  frame,  a  faintly  indicat- 
ed negative  picture.  To  bring  it  out,  an  enamel  color,  in  a 
very  impalpable  state,  is  gently  rubbed  over  with  a  soft 
brush  until  the  whole  composition  or  subject  appears  in  a 
perfect  positive  form.  It  is  then  fixed  by  alcohol,  in  which 
a  small  quantity  of  acid,  either  nitric  or  acetic,  has  been 
mixed.  This  mixture  is  poured  over  the  whole  surface,  and 
drained  oif  at  one  corner. 


PEIOTING  WITHOUT  THE  SALTS  OF  SILVER.  309 

When  the  alcohol  has  completely  evaporated,  the  glass  is 
immersed  gently  and  horizontally  in  a  large  dish  of  clean  water, 
and  left  until  the  chromic  solution  is  dissolved,  and  nothing 
remains  but  the  enamel  color  on  the  glass ;  it  is  then  allowed 
to  dry  spontaneously  near  a  heated  stove.  When  dry  it  is 
ready  for  the  kiln. 

Enamel  of  any  color  may  be  used,  so  that  by  a  careful 
registering  a  variety  of  colors  can  be  printed  one  after  the 
other,  so  as  to  obtain  a  perfect  imitation  of  a  picture ;  also 
the  borders  of  any  description  can  be  subsequently  added, 
and  the  plate  again  submitted  to  the  fire. 

Naturally  ceramic  productions  can  be  thus  coated  with 
the  bichromate  photograph,  and  afterward  submitted  to  the 
lire  to  vitrify  the  image. 

White  enamel  is  glass  rendered  milky  by  fusion  with 
oxide  of  tin ;  it  forms  the  basis  of  many  of  the  colored 
enamels,  which  receive  their  tinge  from  the  metallic  oxides. 
Thus  the  purple  of  Cassius  (gold)  imparts  a  fine  ruby  tint. 
The  oxide  or  phosphate  of  silver  gives  a  yellow  color.  The 
oxides  of  iron  communicate  blue,  green,  yellow  and  brown, 
according  to  quantity  or  state  of  oxidizernent.  The  oxides 
of  copper  produce  a  rich  green,  and,  when  mixed  with  tar- 
tar, a  red  color.  Antimony  yields  a  rich  yellow.  The  black 
oxide  of  manganese  in  excess  forms  black  glass  ;  in  smaller 
quantities,  various  shades  of  purple.  The  oxide  of  cobalt 
imparts  beautiful  blues  of  various  shades,  and  with  the  yel- 
low of  antimony  or  lead  it  produces  green.  Chrome  yields 
greens  and  reds  according  to  the  state  of  oxidizernent. 


CHAPTER  XLI. 


STEEEOSCOPICITY, 

The  property  of  seeing  objects  in  relief  has  occupied  the 
attention  of  philosophers  from  the  ea/liest  periods  ;  and 
various  reasons  have  been  given  for  its  existence.  I  have 
no  hesitation  in  pronouncing  them  all  false,  excepting  the 
one  which  I  have  published  myself.  The  fact  exists  :  we 
see  objects  in  relief— what  is  the  meaning  of  this  expression  ? 
Simply  this  :  we  can  see  at  long  and  short  distances  at  the 
same  time.  But  the  eye  is  a  veritable  lens,  a  corrected  lens, 
and  is  subject  to  the  ordinary  laws  of  optics  ;  the  conjugate 
foci  of  objects  at  different  distances  are  not  on  the  same 
plane  but  at  different  distances  ;  the  retina,  therefore,  is 
not  a  surface,  it  is  a  substance  having  depth,  and  in  this 
depth  are  found  those  conjugate  foci  of  the  different  objects, 
producing  thus  in  the  sensitive  and  transparent  substance  a 
miniature  solid  picture.  This  is  the  simplest  means  to  meet 
the  end  in  view  ;  and  the  Almighty  makes  use  of  the  sim- 
plest means,  and  these  means  I  think  I  have  understood  and 
analyzed.  To  see  long  and  short  distances  at  the  same  time, 
that  is,  to  see  objects  in  relief,  requires  the  possession  of  a  retina 
of  the  depth  of  about  T£o  of  an  inch  in  sensitiveness — now 
this  is  all  that  is  required — the  action  of  the  ciliary  nerve,  the 
motion  of  the  ciliary  muscle,  the  layer-like  structure  of  the 
crystalline  lens,  the  action  of  the  various  straight  and  oblique 
muscles  of  the  eye,  the  effect  of  the  will,  of  the  optic  arteries, 
and  numerous  other  contrivances,  all  these  are  not  required 
in  the  production  of  this  happy  effect. 

Euclid,  it  appears,  though  I  know  not  where,  attributes 
this  phenomenon  to  the  simultaneous  impression  of  two  dis- 
similar images  of  the  same  object  in  either  eye  of  the  observer. 

Arago  writes  that  when  we  see  an  entire  object,  the  phe- 
nomenon is  attributable  to  the  rapidity  of  the  action  of  the 
eye  passing  in  quick  succession  from  one  part  to  another. 

Pouillet's  theory  is  this  :  he  says  that  the  crystalline  lens 
consists  of  ellipsoidal  layers  superposed  one  over  the  other, 


STEREOSCOPICITY. 


311 


endowed  with  the  property  of  acting,  that  is,  of  refracting 
light  independently  of  each  other,  or  simultaneously. 

Some  authors  maintain  that  the  crystalline  lens  is  moved 
by  the  ciliary  muscle  from  or  toward  the  retina  with  great 
rapidity  during  the  action  of  the  perception  of  relief. 

Some  maintain  that  the  cornea  is  made  to  change  its  form 
by  the  instrumentality  of  some  muscular  action  and  thus  to 
accommodate  itself  to  different  distances,  or  to  compensate 
for  the  change. 

Others  again  entertain  the  hypothesis  that  the  eye-ball  is 
either  elongated  or  compressed  by  some  muscular  action, 
just  as  the  distance  is  shorter  or  longer. 

As  I  said,  all  these  hypotheses  seem  to  be  false,  because  the 
minutest  investigations  have  not  yet  discovered  that  the  eye 
is  elongated  or  compressed,  that  the  crystalline  lens  is  ad- 
vanced or  drawn  back,  that  the  crystalline  lens  is  endowed 
with  independent  optical  layers,  that  the  ciliary  muscle  acts 
as  described,  that  the  cornea  is  in  any  way  changed  during 
the  act  of  any  perception.  On  the  contrary,  it  is  known  to 
be  a  positive  fact,  that  a  single  eye  has  a  correct  perception  of 
relief — that  many  animals,  such  as  ducks,  fish,  etc.,  have 
their  eyes  located  in  such  a  position  as  not  to  allow  the 
simultaneous  action  of  either  eye  on  all  occasions  ;  it  is  sup- 
posed, however,  they  see  as  perfectly  as  human  beings.  It 
is  a  well-known  fact  that  we  can  see  near  and  distant  objects, 
as  for  instance,  the  moon,  a  cloud,  a  church  steeple,  and  the 
branches  of  a  tree  close  by,  without  any  change  of  the  eye, 
and  without  any  effort.  It  has  been  furthermore  ascertained 
by  microscopical  examinations  that  the  retina  has  thickness, 
transparency  through  this  thickness,  and  is  constituted  of  a 
conical  or  stick-like  juxta-collocation  of  nervous  material 
from  before  backward,  which  we  have  a  right  to  suppose 
sensitive  to  the  impressions  of  light  throughout.  With  such 
a  constitution  of  nerves  the  problem  of  long  and  short  dis- 
tance, or  the  problem  of  seeing  in  relief,  is  solved. 

The  problem  of  seeing  pictures  in  relief,  depends  primari- 
ly upon  the  property  which  the  eye  possesses  of  seeing 
objects  in  relief ;  for  if  the  eye  were  not  endowed  with  this 
power,  pictures  as  well  as  objects  would  be  seen,  as  it  were, 
projected  flat  on  the  ground  glass  of  the  camera.  This  de- 
pends secondarily  on  the  combined  action  of  two  eyes  ;  for 
a  single  eye  can  by  no  contrivance  see  any  picture  optically 
in  relief. 

It  appears  that  Leonardo  da  Vinci  has  touched  upon  the 
subject  of  binocular  vision  in  one  of  his  manuscripts.  This 


312 


STEREOSCOPICITY. 


distinguished  painter  and  scholar  was  born  in  1452.  There 
is  nothing  positive  in  any  thing  he  has  left  us  about  the  pow- 
er and  rationale  of  seeing  pictures  in  relief. 

The  same  may  be  said  also  of  Giovanni  Battista  Delia 
Porta  and  of  Francis  Aguillon,  who  both  seem  to  have  had 
some  knowledge  of  binocular  perception. 

The  first  definite  and  positive  acquaintance  with  this  pe- 
culiar property  is  of  modern  date  and  is  mentioned  in  1832 
in  the  third  edition  of  Mayo's  Outlines  of  Human  Physiolo- 
gy. Wheatstone's  reflecting  stereoscope  appeared  in  1838  ; 
it  appears  from  the  evidence  of  Newmann,  of  Regent  street, 
London,  that  Wheatstone  was  acquainted  with  a  refracting 
prism  that  would  produce  the  same  effect.  Brewster's  refract- 
ing stereoscope  appeared  in  1850.  Since  its  discovery  by 
Brewster  and  its  manufacture  originally  by  the  celebrated 
opticians,  Soleil  and  Dubosc  in  Paris,  stereoscopicity  has  oc- 
cupied the  attention  of  philosophers  and  amused  the  public  as 
much  as  photography  itself,  which  has  been  the  means,  in 
its  turn,  of  rendering  the  stereoscopes  so  popular.  Without 
photography  the  stereoscope  would  be,  like  the  kaleidoscope, 
a  mere  philosophical  toy. 

The  way  in  which  photography  has  extended  the  influence 
of  stereography  is  attributable  to  the  facility  it  gives  of  ob- 
taining consentaneously  two  dissimilar  pictures  of  the  same 
object  in  the  exact  conditions  as  they  would  be  depicted  by 
either  eye  of  the  spectator  ;  for  it  is  a  well-known  fact  now 
that  these  pictures  are  endowed  with  differences  depending 
upon  the  parallax  of  the  object  on  the  base  line  between  the 
two  eyes  ;  the  greater  the  parallactic  angle,  the  greater  the 
angular  displacement  of  either  picture  in  reference  to  the 
other. 

For  example,  let  a  spectator  stand  before  a  pane  of  glass 
looking  upon  a  church  for  instance.  At  the  distance  of 
distinct  vision  from  the  glass  fix  a  metallic  plate  containing 
two  small  apertures,  separated  by  a  distance  equal  to  that 
between  the  two  eyes.  Let  the  observer  now,  by  means  of 
a  style  dipped  in  thick  printer's  ink,  trace  the  outline  of  the 
church  on  the  glass  as  seen  through  the  aperture  of  the  right 
eye ;  in  like  manner,  let  him  do  the  same  through  the  aper- 
ture of  the  left  eye.  He  will  find  that,  instead  of  one  church, 
two  sketches  will  appear  on  the  glass  side  by  side,  endowed 
with  the  following  property  as  characteristically  distinct 
from  two  engravings  of  the  same  object  from  the  same  plate. 
With  a  pair  of  compasses  measure  the  distance  between 
two  corresponding  points  on  the  church  which  are  nearest 


STEEEOSCOPICITY. 


313 


to  the  observer  ;  measure  also  the  distance  between  two  cor- 
responding points  that  are  the  most  distant  from  the  observ- 
er, it  will  be  found  that  the  latter  measurement  will  exceed 
in  length  that  of  the  former  ;  and  that  this  result  will 
always  be  obtained  ;  that  is,  the  greater  the  distance  of 
certain  parts  of  the  objects  comprehended  in  a  picture  from 
the  point  of  observation,  the  greater  the  difference  of  dis- 
tance between  two  corresponding  points  in  the  foreground 
and  two  in  the  distant  background.  It  will  be  found,  more- 
over, that  the  distance  between  two  corresponding  points 
which  are  very  remote  from  the  eyes,  or  properly  speaking 
at  an  infinite  distance,  is  equal  exactly  to  the  distance 
between  the  eyes  of  the  observer. 

The  parallactic  angle  is  that  angle  which  is  comprehended 
between  the  axes  of  the  eyes  converging  to  a  given  point ; 
and  the  distances  between  any  two  corresponding  points  is 
equal  to  twice  the  versed  sine  of  the  parallactic  angle  ;  but 
the  versed  sine  of  an  angle  is  complementary  to  the  sine, 
and  the  sine  varies  as  the  angle ;  thus,  therefore,  as  the 
sine  decreases,  the  versed  sine  increases  ;  and  in  like  man- 
ner the  distances  between  corresponding  points  from  ante- 
rior to  remoter  positions  in  the  background  will  gradually 
increase.  Such  are  the  properties  inherent  in  the  two 
pictures  of  the  same  object  as  depicted  on  the  retina  of 
either  eye,  or  on  the  ground  glass  of  a  binocular  camera. 
Two  photographs  or  pictures  taken  as  thus  described,  side 
by  side,  are  the  mere  interception  of  rays  on  a  flat  surface 
as  they  proceed  from  the  object.  It  is  natural  therefore  to 
suppose  that  these  pictures,  when  beheld  by  the  eyes,  ought 
to  give  an  impression  of  the  reality  in  relief.  By  a  minute 
investigation  of  the  subject  it  is  ascertained  that  conditions 
arise  for  the  effectuation  of  this  result,  which  at  the  first 
sight  are  not  anticipated.  One  condition  is  to  obtain  the 
same  convergence  of  the  axes  of  the  eyes  as  existed  when 
the  pictures  were  taken.  To  obtain  this  convergence  is  an 
effort  for  the  eyes  ;  and  on  this  account  there  are  but  few 
persons  who  possess  such  perfect  command  of  their  eyes 
as  to  secure  the  right  convergence  for  given  pictures.  It 
is  far  from  being  absolutely  necessary  that  the  convergence 
should  be  exactly  the  same  as  existed  originally  when  the 
photographs  were  taken  ;  there  are,  however,  certain  limits 
on  either  side,  that  is,  it  may  be  a  little  either  greater  or 
less  than  that  of  the  parallactic  angle. 

The  object  of  this  convergence  is  a  very  essential  point  in 
binocular  perception  producing  relief ;   and  the  rationale  of 
14 


314 


STEREOSCOPICITY. 


this  perception  of  relief  is  not  lucid  on  other  grounds  than 
that  which  admits  of  the  production  of  a  virtual  solid  image 
in  space,  either  at  a  distance  beyond  the  pictures  or  in  front 
of  them.  Such  solid  images  are  formed  in  space  by  the 
intersection  of  the  rays  that  proceed  from  the  corresponding 
points  in  either  picture  ;  for  these  rays,  when  they  pass  the 
optic  centers  of  the  eyes,  form  different  parallactic  angles, 
according  as  the  distances  apart  are  different,  and  thus  in- 
tersect at  variable  distances  corresponding  with  the  points 
in  the  real  object  from  which  the  pictures  were  taken. 

Some  eyes  have  a  very  great  facility  of  converging  their 
axes  ;  in  which  case  the  rays  from  corresponding  points  in- 
tersect in  front  of  the  pictures  and  very  nearly,  if  not  exactly, 
at  a  distance  half-way  between  the  pictures  and  the  eyes  ; 
in  this  case,  (as  may  be  seen  on  referring  to  this  subject 
discussed  at  large,  page  73,  etc.,  Vol.  XIV.  of  Humphrey's 
Journal)  the  effect  of  relief  is  inverted,  the  most  distant 
points  being  projected  forward,  whilst  the  anterior  points 
are  seen  in  the  extreme  background.  This  is  the  natural 
consequence  of  the  intersection  of  lines  at  angles  that  depend 
upon  the  peculiar  distance  apart  of  the  corresponding  points 
in  the  pictures. 

Where  eyes  do  not  possess  this  great  degree  or  facility 
of  convergence,  the  intersections  will,  with  the  same  degree 
of  geometrical  consequence,  take  place  beyond  the  pictures 
and  at  variable  distances  beyond.  The  solid  picture  in  this 
case  will  not  be  inverted  ;  but  it  will  vary  in  magnitude  ac- 
cording as  the  intersections  occur  nearer  to  the  pictures  or 
farther  from  them.  Persons,  therefore,  endowed  with  this 
less  degree  of  convergence,  have  the  pleasure  of  beholding 
a  magnified  solid  picture,  of  which  the  magnitude  is  some- 
times very  great ;  whereas,  those  whose  optical  axes  can 
easily  converge,  see  a  solid  image  uniformly  of  half  the  size 
of  the  pictures,  but  which  is  on  this  account  very  sharp  and 
pleasing. 

All  eyes  can  be  tutored  with  very  little  difficulty  to  re- 
ceive this  impression  of  relief  from,  two  photographs  pos- 
sessing the  conditions  required. 

In  order  that  the  solid  picture  in  the  latter. case  shall  be 
direct,  that  is,  not  pseudoscopic,  the  pictures  must  be  invert- 
ed, the  left  being  pasted  upon  the  right  side  ;  and  the  right 
on  the  left  side.  Two  photographs,  so  mounted,  I  have  de- 
nominated a  Strabonic  Stereograph,  to  distinguish  it  from 
the  ordinary  stereograph. 

Another  condition,  in  order  to  see  pictures  in  relief,  by 


STEREOSCOPICITY. 


315 


the  binocular  perception,  is  the  cosentaneous  independent 
action  of  either  eye.  From  this  circumstance  either  eye 
beholds  the  two  images  ;  but  the  two  interior  ones  intersect, 
are  therefore  superimposed  and  form  thus  only  one  image, 
which  is  the  solid  image ;  the  two  outside  images  are  flat, 
and  do  not  attract  the  attention  to  any  great  extent,  by  rea- 
son of  the  superior  brilliancy  of  the  middle  picture.  The 
rationale  of  this  delightful  phenomenon,  as  hitherto  given  in 
all  our  text-books  on  the  subject,  is  so  far  erroneous,  from 
the  fact  that  it  is  asserted  that  each  eye  sees  its  correspond- 
ing picture  as  the  object  was  seen  when  the  pictures  were 
taken.  If  this  were  true,  we  ought  to  see  only  the  solid 
image,  and  not  the  two  outside  flat  pictures. 

All  the  instruments,  called  stereoscopes,  are  mere  optical 
contrivances  whereby  in  the  first  place  the  requisite  con- 
vergence is  obtained  with  facility ;  secondly,  they  magnify 
the  image  in  relief ;  and  thirdly,  they  shut  off  the  two  out- 
side flat  pictures.  They  are  not  essential  at  all  to  the  per- 
ception of  relief  furthermore  than  as  accessories.  The  phi- 
losophy of  stereoscopicity  is  very  simple,  it  is  founded  solely 
on  the  production  of  intersections  of  rays  from  corresponding 
points  of  two  pictures,  the  distance  of  which  points  must  be 
endowed  with  the  requisite  differences  ;  from  these  intersec- 
tions or  superimpositions  a  virtual  solid  image  is  formed 
which  is  then  regarded  as  a  real  object,  which  produces  the 
perception  of  relief  in  either  eye,  because  the  conjugate  pic- 
ture in  the  retina  is  also  solid. 

It  is  evident,  then,  that  a  single  eye  can  never  see  a  flat 
picture  in  relief,  because  the  requisite  intersections  can  not 
take  place ;  but  we  are  by  no  means  allowed  to  argue  from 
this  that  a  single  eye  can  not  appreciate  relief  or  distance 
in  real  objects,  or  that  relief  is  the  result  of  binocular  per- 
ception. This  is  an  absurdity  into  Avhich  many  investiga- 
tors of  nature  have  fallen  ;  they  have  not  comprehended  the 
true  origin  of  this  perception,  which  depends  upon  the  sen- 
sitiveness*of  the  retinal  film  through  a  certain  thickness,  and 
not  alone  on  a  surface. 

Eyes  may  be  tutored  to  see  two  photographs  in  relief  by 
the  following  expedients,  and  without  the  aid  of  stereoscopes. 

All  persons  accustomed  to  close  reading  or  writing,  or 
to  the  use  of  magnifying  spectacles  are  more  inclined  to  see 
strabonically  than  otherwise.  They  can,  in  plain  language, 
easily  squint  inwardly  and  see  the  end  of  the  nose. 


316 


STEREOSCOPICITY. 


Strdbonic  Stereograph. 

In  the  first  place,  therefore,  prepare  a  number  of  strabonic 
stereographs  of  architectural  structures,  as  follows  :  "  Take 
the  ordinary  stereographs  of  the  views  in  question  and 
throw  them  into  a  pail  of  water  until  the  photographs  easily 
separate  from  the  mounts.  Remove  the  photographs,  and 
passing  over  the  backs  with  a  sponge  dipped  in  starch  paste, 
transpose  them  upon  the  original  mounts  or  upon  new  ones  ; 
that  is,  fix  the  right-hand  photograph  on  the  left  side,  and  vice 
versa.  The  student  next  has  to  learn  to  see  double.  This  is 
effected  by  holding  up  the  thumb  before  the  eyes,  so  as  to  see 
two  thumbs  ;  when  he  is  expert  at  this,  let  him  next  hold  up 
in  front  of  his  eyes,  at  the  regular  reading  distance,  both  his 
thumbs,  and  try  if  he  can  see  four  thumbs.  As  soon  as  this 
is  effected,  then,  by  bringing  the  thumbs  closer  together,  so 
that  their  distance  apart  is  about  two  inches  and  a  half,  the 
two  middle  ones  can  be  made  to  overlap  each  other,  where- 
by  three  thumbs  will  appear.  The  difficulty  is  now  over- 
come; for  the  eyes,  when  well-practised  in  this  strabonic 
exploit,  are  prepared  for  regarding  a  stereograph  which  is 
mounted  as  above  described,  when,  with  a  little  patience, 
three  photographs  will  appear,  of  which  the  middle  one 
will  be  very  distinct,  finely  defined,  and  in  full  and  natural 
relief,  exhibiting  all  the  solidity  of  reality. 

The  two  outside  pictures  are  indistinct,  and  the  eyes  will 
soon  learn  to  neglect  them ;  or  they  may  be  entirely  removed 
from  the  field  of  view  by  the  use  of  a  frustum  of  a  pyramid 
formed  of  cardboard,  whose  height  is  equal  to  half  the  dis- 
tance of  distinct  vision,  that  is,  half  the  reading  distance; 
the  side  of  its  upper  base  one  inch  and  a  quarter,  and  that 
of  the  lower  three  inches.  By  placing  the  lower  base  next 
the  eyes  and  looking  through  it,  the  stereoscopic  picture  will 
appear  alone  and  distinct. 

The  second  method  is  founded  on  a  reverse  principle,  that 
is,  by  excluding  the  rays  of  light  from  the  middle  of  the 
field  of  view,  comprehending  a  space  of  one  inch  and  a  quar- 
ter square.  This  is  effected  by  placing  a  piece  of  cardboard 
of  this  width  in  the  middle,  half-way  between  the  eyes  and 
the  photographs,  of  which  the  latter  are  fixed  at  the  regular 
reading  distance  ;  or  the  same  object  can  be  effected  as  fol- 
lows :  Take  a  slip  of  wood  about  two  feet  long,  two  inches 
wide  and  one  inch  thick;  take  secondly,  a  piece  of  card- 
board of  the  size  of  a  stereograph,  and  bisect  the  two  par- 
allel sides  and  the  two  parallel  ends,  and  join  the  points  of 


STEREOSCOPICITY. 


317 


bisection.  Where  these  lines  meet  we  have  the  center  of 
the  cardboard.  From  this  point  right  and  left  on  the 
larger  line,  mark  off  a  space  one  inch  and  a  quarter  in  length, 
and  at  either  extremity  thus  marked  off  draw  a  circle  half 
an  inch  in  diameter.  Lay  the  slip  of  wood  on  its  flat  sur- 
face on  a  table,  and  tack  the  piece  of  cardboard  to  one  end 
of  the  slip  at  right  angles  to  the  table,  with  an  equal  portion 
of  cardboard  projecting  at  either  end.  Previously,  however, 
the  wide  surface  of  the  slip  must  be  divided  longitudinally 
into  two  halves,  by  running  a  saw  from  end  to  end  so  as  to 
form  a  groove  about  a  quarter  of  an  inch  deep ;  and  at  a 
distance  from  the  cardboard,  at  the  end,  equal  to  the  reading 
distance,  another  groove  is  sawed  at  right  angles  to  the  for- 
mer and  of  the  same  depth ;  in  the  latter  groove  an  ordinary 
stereograph  is  placed,  and  along  the  longitudinal  groove  a 
piece  of  cardboard  at  right  angles  to  it.  Now  let  the  ob- 
server look  through  the  two  apertures  at  the  stereograph ; 
it  is  evident  that  the  right  eye  can  see  only  the  right  photo- 
graph, whilst  the  left  eye  is  restricted  in  like  manner  to  the 
left.  By  concentrating  the  individual  attention  of  each  eye 
to  its  respective  picture,  by  pressing  the  external  parts  of 
the  ball  of  either  eye  with  the  fingers,  or  by  compressing 
the  eyes  as  in  frowning,  the  two  pictures  may  be  caused  to 
overlap  each  other,  when  a  new  picture  will  appear  possess- 
ed of  the  full  stereoscopic  effect,  apparently  of  a  larger  size 
than  the  originals.  The  magnitude  in  this  case  will  vary 
with  the  angle  of  convergence ;  if  this  should  happen  to  be 
the  same  as  that  formed  by  the  axes  of  the  eyes  or  the 
lenses  when  the  pictures  were  taken,  the  solid  picture  will 
be  of  the  same  size  as  the  apparent  size  of  the  object  from 
which  the  photographs  were  taken ;  at  all  other  degrees 
of  convergence  the  magnitude  will  vary. 

Now  the  solid  picture,  produced  by  either  process,  can  be 
magnified  ad  libitum  by  meLns  of  eye-lenses  or  spectacles ; 
and  when  these  eye-glasses  are  fixed  in  proper  receptacles, 
they  are  then  deiaominated  refracting  stereoscopes ;  but  it 
will  be  seen  that  they  are  far  from  being  indispensable  ;  they 
are,  in  fact,  mere  accessories. 

The  differences  of  distance  between  the  corresponding 
points  on  two  photographs  taken  stereographically,  being 
functions  of  the  parallactic  angle,  can  be  easily  calculat- 
ed, and  consequently  artificial  stereographs  can  be  deline- 
ated geometrically.  The  results  drawn  from  such  calculations 
furnish  means  for  detecting  the  inherent  properties  of  stereo- 
scopicity  or  their  total  absence  in  any  given  photographs  or 


318 


STEREOSCOPICITY. 


designs.  In  this  way  it  was  conclusively  determined  that 
the  drawings  of  Chimenti  were  not  stereoscopic.  Pages  of 
print  can  be  set  stereoscopically,  so  that  one  line  alternately 
stands  above  the  other,  or  in  any  way  whatever.  The  fol- 
lowing is  a  typographic  stereograph.  It  is  formed  by  set- 
ting the  alternate  lines  at  different  distances  from  one  anoth- 
er ;  that  is,  the  distance  from  T  to  T  in  the  first  lines  is 
greater  by  about  one  sixteenth  of  an  inch  than  the  distance 
from  H  to  H  in  the  second  lines  ;  and  all  the  rest  are  set  ac- 
cordingly. Viewed  by  the  stereoscope  the  odd  lines  will  be 
seen  standing  far  back  behind  the  even  lines  ;  an  increase  of 
difference  will  throw  the  odd  lines  still  further  back  into  the 
background.  An  irregularity  of  difference  produces  an  ir- 
regularity in  the  relief. 


STEREOSCOPICITY. 


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CHAPTER  XLIL 


CELESTIAL  PHOTOGRAPHY. 

Within"  the  last  few  years  the  importance  of  the  applica- 
cation  of  photography  to  astronomical  investigations,  as 
well  as  to  meteorology,  has  been  recognized  by  natural  phi- 
losophers as  a  definite  help-mate  in  the  prosecution  of  these 
studies.  This  application  consists,  when  referred  to  astron- 
omy, in  obtaining  photographs  and  stereographs  of  the  moon 
in  its  various  phases,  of  the  sun,  of  the  planets,  and  of  the 
comets;  and,  when  referred  to  meteorology,  in  obtaining 
photographic  delineations  of  the  different  classes  of  clouds ; 
of  the  aurora  borealis  in  its  various  configurations,  of  me- 
teors, halos,  water-spouts,  paraselenes,  etc. 

For  this  purpose  the  various  forms  of  telescopes,  both  re- 
flecting and  refracting,  may  be  employed,  which  are  used  in 
observatories.  Refracting  telescopes,  from  the  fact  of  their 
objectives  being  corrected  for  the  luminous  part  of  the  spec- 
trum, are  far  from  being  corrected  for  photographic  purposes  ; 
and  the  ground  glass  has  sometimes  to  be  moved  as  much  as 
an  inch  from  the  position  of  the  luminous  focus  before  the  ac- 
tinic focus  is  arrived  at.  Reflecting  telescopes,  on  the  con- 
trary, not  decomposing  light,  have  to  undergo  no  correction 
for  actinism.  For  amateur  astronomical  photographers  sil- 
vered glass  mirrors,  as  recommended  by  Steinheil,  are  most 
easily  constructed,  are  comparatively  cheap,  and  from  their 
lightness  very  manageable.  These,  when  properly  mounted, 
will  give  a  picture  of  the  moon,  etc.,  of  a  magnitude  vary- 
ing with  the  focal  length  of  the  mirror.  The  ground  glass 
is  placed  in  the  principal  focus  of  the  objective  or  reflector, 
and  has  a  motion  by  which  it  can  be  adjusted  to  accuracy. 
In  such  cases  the  eye-pieces  are  removed.  When  the  opera- 
tion is  not  instantaneous,  the  telescopes  have  to  be  furnished 
with  clock-work,  by  means  of  which  the  axis  of  the  body 
photographed  can  always  be  made  to*  coincide  with  the  axis 
of  the  telescope,  during  the  time  of  exposure. 

We  are  indebted  to  Messrs.  Bond  of  Cambridge,  Crookes, 


CELESTIAL  PHOTOGRAPHY. 


321 


De  la  Rue,  Hartnup,  Forrest,  Edwards,  Berry,  Hodgson, 
Secchi,  etc.,  for  interesting  information  and  photographs  of 
celestial  objects. 

The  moon  naturally  claimed  the  first  attention  ;  the  Bonds 
were  the  first  to  obtain  a  daguerreotype  of  this  satellite; 
Messrs.  Hartnup,  Forrest,  Berry,  and  Edwards  obtained 
very  beautiful  photographs  on  collodion  of  the  moon  in 
1854,  of  an  inch  and  one  third  in  diameter,  which  they  after- 
ward magnified  a  few  diameters  on  another  collodion  plate, 
and  then  exhibited  the  photographic  representation  on  a 
large  screen  sixty  feet  in  diameter,  the  picture  having  been 
magnified  to  this  extent  by  means  of  a  magic  lantern. 

At  the  same  time  Mr.  Hartnup  suggested  a  plan  of  taking 
a  stereograph  of  the  moon,  by  first  taking  a  photograph  of 
this  luminary  twelve  hours  before  full,  and  then  twelve  hours 
after  full,  thus  changing  the  shadows  from  one  side  to  the 
other.  The  stereograph  was  successful,  and  exhibited  the 
moon  in  relief.  From  the  fact  that  the  moon  revolves  on 
her  axis  in  the  same  period  that  she  revolves  in  her 
orbit,  it  is  difficult  to#  obtain  a  degree  of  parallax  by 
which  more  of  one  side  can  be  seen  at  one  time  than  at 
another  ;  but  the  axis  of  the  moon,  that  is,  the  moon  itself 
in  the  direction  of  its  axis,  has  a  sort  of  libration,  which 
brings  to  light  alternately  more  of  the  northern  parts  than 
of  the  southern.  By  taking  photographs  at  these  different 
periods  a  sufficient  amount  of  parallactic  angle  has  been 
obtained,  and  perfect  stereographs  have  been  the  result. 
The  moon  has  been  photographed  and  stereographed  in 
all  her  phases  ;  the  shadows  of  the  mountains  are  so  well 
delineated  in  these  different  phases  as  to  admit  an  accurate 
measurement  of  the  height  and  diameter  of  those  mountains. 

A  few  seconds'  exposure  with  a  good  equatorial  will,  in 
general,  give  a  tolerable  negative.  It  is  not  absolutely  ne- 
cessary to  be  furnished  with  a  telescope  in  order  to  get  a 
photograph  of  the  moon  ;  the  photographer  will  be  glad  to 
learn  that  a  long-focussed  view-tube  will  permit  him4o  ob- 
tain a  copy  of  this  bright  luminary,  of  about  half  an  inch  in 
diameter,  which  can  afterward  be  magnified  to  any  size  de- 
sired. The  only  difficulty  is  to  keep  the  moon  in  exactly 
the  same  position  of  the  ground  glass  for  a  number  of 
seconds. 

The  sun  is  easily  photographed,  because  the  operation  is 
instantaneous.    The  act  of  focussing  is  performed  by  placing 
a  piece  of  violet-colored  glass  over  the  opening  of  the  ob- 
jective, which  is  retained  there  during  the  exposure.  In 
14* 


322 


CELESTIAL  PHOTOGRAPHY. 


this  way  eclipses  of  the  sun  can  be  photographed  without 
that  immense  trouble  and  risk  which  have  been  so  often  re- 
ferred to  in  celestial  photography. 

The  stars  have  a  high  degree  of  photogenic  power,  and 
can  be  photographed  in  accordance  with  the  intensity  of  their 
light.  Mr.  Bond  has  endeavored  to  base  upon  this  power  a 
means  of  classifying  the  stars  into  magnitudes,  which  at 
present  are  quite  arbitrary. 

The  planets,  possessing  much  less  photogenic  power  than 
the  fixed  stars,  are  in  consequence  not  so  easily  photograph- 
ed ;  but  by  means  of  well-regulated  clock-work,  De  la  Rue 
has  succeeded  in  obtaining  very  excellent  photographs  of 
Jupiter  and  his  bands,  Saturn  and  his  rings,  as  also  a  stereo- 
graph of  Mars,  by  taking  two  photographs  at  an  interval  of 
two  hours,  and  others  of  Saturn  at  an  interval  of  three  years 
and  a  half. 

It  is  supposed  there  are  planets  nearer  to  the  sun  than 
Mercury,  which  have  not  been  discovered  by  reason  of  their 
proximity  to  the  solar  orb  :  it  is  hoped,  however,  by  means 
of  photography  to  settle  this  supposition ;  for  if  at  any  time 
in  any  of  the  numerous  photographs  which  are  taken  of  the 
sun,  a  small,  round  black  speck  should  be  discovered,  the 
conclusion  of  the  existence  of  another  inferior  planet  would 
soon  be  drawn. 

De  la  Rue  is  prosecuting  this  branch  of  photography  and 
astronomy  with  great  zeal  and  success ;  his  labors,  too,  are 
highly  appreciated.  The  Astronomical  Society  of  London 
have  conferred  upon  him  their  annual  large  medal  as  a  token 
of  their  high  appreciation  of  his  merits  and  the  results  of 
his  labors. 


CHAPTER  XLIII. 


HELIOCHROMY,  OR  THE   ART   OF   TAKING   PHOTOGRAPHS  IN 
NATURAL  COLORS. 

Sir  John  Herschel  observed  in  1840,  that  paper,  prepared 
with  chloride  of  silver  and  blackened  in  the  sun,  when  ex- 
posed beneath  red  or  blue  glass,  assumed  the  respective  color 
of  the  glass;  and  Edmond  Becquerel  in  1847  and  1848  pro- 
duced all  the  colors  of  the  spectrum  on  a  prepared  silver 
plate,  which  were  permanent  as  long  as  the  plate  was  kept 
in  the  dark.  The  surface  was  sensitized  by  immersing  the 
plate  either  in  a  solution  of  a  bichloride,  or  in  chlorine  water. 

Niepce  de  St.  Victor,  following  in  the  steps  of  Becquerel, 
is  obstinately  persevering  in  his  attempts  to  fix  the  colors 
which  can  already  be  obtained.  The  production  of  colors  is 
a  fact ;  the  fixation  of  colors  is  still  a  problem  unsolved. 

The  plate  for  heliochromic  purposes  is  best  prepared  in  the 
following  manner :  A  common  daguerreotype  plate  is  var- 
nished on  the  copper  side.  In  one  corner  a  hole  is  bored  in 
order  that  the  plate  can  be  suspended  on  a  silvered  copper 
wire,  which  is  the  positive  pole  of  a  galvanic  battery.  A 
small  plate  of  platinum  soldered  to  a  copper  wire  forms  the 
negative  or  zinc  pole.  As  soon  as  the  battery  is  in  working 
condition,  insert  the  two  poles  at  the  proper  distance  in  a 
vessel  containing  a  mixture  of  one  part  of  hydrochloric  acid 
and  eight  parts  of  water.  By  the  electrolytic  decomposition 
hydrogen  affects  the  negative  pole  and  is  given  off  there, 
whereas  chlorine  goes  to  the  silvered  plate,  combines  with 
the  silver,  and  forms  a  chloride.  The  operation  is  best  per- 
formed in  the  dark-room.  The  amount  of  deposition  is  re- 
cognized by  the  different  shades  of  cblor  which  the  plate  as- 
sumes.   The  thinner  the  film,  the  more  sensitive  it  is. 

Niepce  de  St.  Victor  has  recommended  the  production  of 
this  sensitive  film  by  immersing  the  plate  in  soluble  bichlo- 
rides, or  in  chlorides  in  combination  with  copper  salts. 

In  whichever  way  prepared,  the  plate  is  dried  over  the 
flame  of  a  spirit-lamp,  and  the  surface  is  gently  brushed  over 


324 


PHOTOGRAPHS  IN  NATURAL  COLORS. 


jvith  a  tuft  of  cotton,  in  order  to  remove  a  downy  substance 
arising  from  impurities. 

If  this  plate  be  expose^,  to  a  diffused  light,  the  film  assumes 
a  grayish  violet  tinge  ;  but  if  it  be  exposed  to  a  well-defined 
and  very  luminous  spectrum,  it  receives  an  impression  of  the 
various  colors  of  this  spectrum,  but  not  with  the  same  facil- 
ity. The  orange,  the  yellow,  and  the  red  are  the  first  colors 
that  appear,  and  the  first  to  darken  and  to  become  gray  by 
a  continued  action.  Beyond  the  red  a  rosy  hue  is  made 
manifest,  but  this  darkens  the  first  of  all.  The  blue,  the 
green,  and  the  violet  are  the  most  vivid.  Beyond  the  ter- 
mination of  the  violet  part  of  the  spectrum  there  is  a  decom- 
position of  a  gray  color. 

By  keeping  the  prepared  plates  exposed  to  a  temperature 
of  about  100°  for  forty-eight  hours  in  a  stove,  or  to  the  rays 
of  the  sun  beneath  a  piece  of  red  glass,  the  film  becomes 
much  more  sensitive,  and  not  only  reproduces  the  spectrum 
but  receives  an  impression  from  white  light. 

If,  when  the  plate  leaves  the  electrolytic  bath,  it  be  sim- 
ply dried,  without  raising  the  temperature  to  such  a  degree 
as  to  change  the  color  of  the  film,  and  after  this  the  plate 
be  exposed  beneath  a  colored  engraving,  a  reproduction  of 
these  colors  will  soon  be  effected ;  some  of  these  are  some- 
times latent,  whilst  others  are  brilliantly  manifest.  Those 
which  are  latent  can  be  developed  by  simply  rubbing  the 
surface  gently  with  a  tuft  of  cotton  impregnated  with  am- 
monia, which  has  been  previously  used  for  cleaning  a  plate. 
It  is  hence  evident  that  a  colored  image  is  already  produced, 
which  may  be  partially  manifest  and  partially  latent. 

Two  very  important  problems  remain  to  be  solved :  to 
find  means  of  developing  the  whole  of  the  image  at  once  in 
all  its  colors,  and  of  fixing  it  when  developed.  Some  colors 
can  be  always  reproduced,  whilst  others  are  but  partially 
obtained.  None  of  the  colors  as  yet  can  be  rendered  per^ 
manent  in  diffused  light.  This  branch  of  photography, 
therefore,  is  still  quite  imperfect.  It  is  difficult  to  form  an 
opinion  as  to  the  possibility  of  the  solution  of  this  interest- 
ing problem  ;  because  as  yet  no  clue,  no  rational  hypothesis 
can  be  given  of  the  cause  of  the  reproduction  of  the  colors 
in  question.  In  the  ordinary  positive  printing  on  the  chlo- 
ride of  silver,  the  cause  of  the  decomposition  is  probably  just 
as  little  understood ;  but  we  are  satisfied  with  almost  any 
theory  as  long  as  the  manipulation  is  definite  in  its  manage- 
ment, and  within  our  power  to  continue  or  restrain.  In  the 
reproduction  of  colors  these  characters  are  wanting,  and  we 


PHOTOGRAPHS  IN"  NATURAL  COLORS. 


325 


are  hence  tempted  to  disbelieve  in  the  possibility  of  the 
effectuation  of  so  desirable  a  discovery.  On  the  other  hand, 
the  very  fact  that  colors  can  be  once  reproduced,  engenders 
faith  in  the  realization  of  the  great  object ;  and  because  a 
similar  and  apparently  equally  as  difficult  case  of  fixation 
of  a  fugitive  image  has  already  been  overcome,  hope  still 
points  to  the  goal  of  final  success. 

Our  knowledge  of  the  image-impressions  by  contact,  by 
the  influence  of  heat  and  of  electricity,  is  limited  simply  to 
the  recorded  facts,  for  which  as  yet  no  satisfactory  rationale 
has  been  assigned.  Probably  all  the  pictorial  representations 
of  objects  in  photography,  and  its  congene  branches,  develop- 
ed either  by  mercury,  pyrogallic  acid,  the  protosalts  of  iron, 
the  breath,  impalpable  powders,  etc.,  may  be  classified  in  one 
and  the  same  category,  of  which  the  cause  may  either  be  a 
molecular  or  polar  change — that  is,  either  an  absolute  change 
of  position  of  the  ultimate  atoms  in  the  aggregated  material, 
or  simply  a  change  in  the  attractions  of  these  atoms.  The 
hypothesis  thus  expressed  is  founded  upon  the  circumstance 
that  every  latent  image  is  developed  by  means  of  matter 
applied  to  the  film,  which  is  attracted  to  certain  parts  after 
exposure  by  apparent  predispositions  in  these  parts,  which 
have  been  superinduced  by  this  exposure ;  the  resulting 
pictures  are  combinations  of  the  new  and  applied  material 
with  the  original  matter  in  the  film.  By  an  extended  course 
of  definite  experiments  applied  understandingly  in  reference 
strictly  to  cause  and  effect,  we  have  a  right,  in  the  course  of 
time,  to  expect  a  definite  solution  of  these  wonderful  manifes- 
tations of  the  presence  of  an  Omniscient  Intelligence. 


CHAPTER  XLIV. 

IMPERFECTIONS    IE"   COLLODION  NEGATIVES  AND  POSITIVES, 
AND   THEIR  REMEDEES. 

The  knowledge  of  an  imperfection  ox  an  error  is  half  the 
correction.  We  must,  therefore,  first  know  what  the  fail- 
ures in  collodion  negatives  and  positives  are.  Their  enu- 
meration is  as  follows: 

Fogginess  /  Spots  and  Apertures  ;  Ridges  and  Undulating 
Lines  ;  Streaks  and  Stains  /  Feebleness  of  the  Image,  or 
Deficiency  of  Contrast  /  Harshness,  or  Excess  of  Contrast; 
Imperfect  Definition  y  Solarization  /  Teitder  and  Rotten 
Films. 

Fogginess. — This  is  a  mist  or  veil-like  appearance  that 
covers  the  whole  negative ;  it  gives  it  a  foggy  or  clouded 
appearance.  This  imperfection  may  be  the  result  of  many 
and  various  causes,  as  for  instance  :  Diffused  light  in  the 
camera  through  holes  or  chinks  ;  reflections  from  white  or 
unblackened  surfaces  in  the  camera  ;  diffused  light  through 
apertures  or  chinks  in  the  door  behind  the  plate  in  the  plate- 
holder  ;  direct  rays  of  the  sun  through  the  objective  or  lens  ; 
an  alkaline,  neutral,  impoverished  or  contaminated  state  of  the 
nitrate  of  silver  bath  ;  a  similar  condition  of  the  collodion  ; 
certain  iodizers  in  the  collodion  and  at  certain  stages  of 
ripening  ;  diffused  light  in  the  dark-room  ;  too  intense  arti- 
ficial light  in  the  dark-room  ;  too  intense  a  development  ; 
fumes  of  ammonia,  of  turpentine,  of  tobacco,  of  hydrosul- 
phuric  acid,  and  probably  almost  of  any  other  volatile 
chemical  substance  in  the  developing-room  ;  imperfect 
cleanness  of  a  glass  plate  that  has  been  used  before  ; 
the  use  of  gutta-percha  baths  and  dippers. 

Diffused  light  in  the  camera,  either  in  front  of  the  plate 
or  behind  it ;  Reflections  from  white  or  unblackened  sur- 
faces in  the  camera. — This  is  a  certain  cause  of  fogging,  and 
can  easily  be  remedied.  Examine  the  camera  carefully  for 
all  chinks  and  holes.    Some  photographers  are  very  care- 


IMPERFECTIONS  AND  THEIR  REMEDIES.  327 


less  ;  they  screw  on  the  flanges  of  various-sized  tubes  on  the 
end  of  the  camera,  and  neglect  filling  the  apertures  left  by 
the  screws  when  withdrawn.  Chinks  occur  invariably  in 
cameras  made  of  green  wood  ;  and  the  bellows  part,  by 
frequent  adjustment,  sometimes  cracks.  The  plate-holder 
has  also  its  imperfections  ;  the  slide  sometimes  allows  the 
entrance  of  light  ;  the  apertures  at  the  bottom,  for  the  pas- 
sage of  accumulating  nitrate  of  silver,  are  frequently  left 
open  and  not  filled  with  sponge,  so  that  light  penetrates  in 
this  way.  The  door  behind  may  close  inaccurately ;  and 
the  plate-holder  may  slide  irregularly  and  not  fill  the  groove 
calculated  to  receive  it.  All  these  are  errors  or  defects  of 
workmanship,  which  must  and  can  be  avoided  or  remedied. 
Look,  therefore,  to  your  camera  first  in  the  search  of  chinks, 
cracks,  and  apertures  ;  secondly,  if  the  inside  surfaces  of 
the  camera  are  not  of  a  dead  black,  cover  them  with  un- 
glazed  black  woolen  or  cotton  cloth,  or  wash  them  over 
with  a  thick  solution  of  ink  or  lampblack. 

Direct  rays  of  the  sun  through  the  axis  of  the  lens. — 
Avoid  this  evil ;  like  many  other  troubles,  to  know  it,  is  its 
total  remedy. 

An  alkaline,  neutral,  impoverished  or  contaminated  state 
of  the  nitrate  of  silver  bath. — Immerse  a  piece  of  reddened 
litmus  paper  in  the  bath,  and  see  whether  it  changes  color, 
after  a  while,  to  a  blue — if  so,  the  bath  is  alkaline. 

First  remedy. — Make  a  mixture  of  six  drops  of  acetic 
acid  in  a  drachm  of  water,  if  you  are  taking  negatives,  and 
of  the  same  quantity  of  nitric  acid  and  water,  if  you  are 
taking  positives  ;  add  ten  drops  at  a  time  of  either  solution 
until  the  fogging  disappears.  Sometimes  even  more  acid 
may  be  required. 

Second  remedy. — Instead  of  adding  acid  to  the  bath,  add 
an  old  collodion  or  tincture  of  iodine  to  your  collodion  in 
present  use  ;  this  frequently  is  the  safest  plan  of  action. 

If  the  bath  is  impoverished,  it  will  at  the  same  time  be 
contaminated.  The  remedy  is  to  boil  it  some  time  in  a 
glass  flask  in  order  to  get  rid  of  the  ether,  alcohol,  and  the 
volatile  substances  produced  by  decomposition,  as  also  to 
coagulate  organic  matter ;  then  allow  the  bath  to  cool,  and 
filter.  To  the  filtrate  add  more  nitrate  of  silver  if  required. 
Placing  an  old  bath  in  the  sun  for  several  days  is  also  of 
great  assistance,  but  it  is  far  from  being  equal  to  boiling  or 
distilling. 

Certain  iodizers  in  the  collodion  and  at  certain  stages  of 
ripening. — Iodide  of  cadmium  alone  frequently  produces 


328  IMPERFECTIONS  AND  THEIR  REMEDIES. 


fogginess  ;  almost  any  new  and  limpid  collodion  has  the 
same  effect.  Add  iodide  of  ammonium  in  the  first  case,  and 
an  old  collodion  or  tincture  of  iodine  in  the  second  case  ; 
the  sensitiveness  will  be  thereby  probably  diminished,  whilst 
the  condition  to  fog  will  be  removed. 

Diffused  light  in  the  dark-room,  or  too  i?itense  an  artificial 
light. — Place  the  artificial  light  behind  a  piece  of  ground 
glass,  and  do  not  bring  it  near  the  negative  until  the  latter 
is  thoroughly  fixed.  Diffused  light  must  be  locked  out  of 
the  room. 

Too  intense  a  developer. — In  summer  less  of  the  devel- 
oper, whether  of  iron  or  pyrogallic  acid,  or  more  of  the 
acid  is  required  than  in  winter,  otherwise  fogging  will  be 
the  consequence— the  property  of  acid  is  to  restrain  the  ac- 
tion of  the  developer  ;  use  your  judgment,  therefore,  and 
do  not  always  keep  to  the  same  amount  of  protosulphate  of 
iron,  or  pyrogallic  acid  to  the  ounce  of  water  in  all  seasons  ; 
nor  restrict  yourself  unconditionally  to  the  same  amount  of 
acid  in  the  developer. 

Fumes  of  ammonia,  etc. — Keep  your  dark-room  solely  for 
its  legitimate  purposes.  Keep  it  rigidly  clean  ;  perform  no 
chemical  experiments  in  it  ;  abjure  smoking  in  this  sanc- 
tum ;  do  not  sensitize  your  papers  or  fuminate  with  ammo- 
nia in  this  room  ;  make  no  manner  of  fumes  therein. 

Imperfect  cleanness  of  the  plate,  etc. — Wash  the  old  plates 
with  a  solution  of  salts  of  tartar  and  water  ;  if  this  does  not 
remove  the  adhering  dirt,  wash  it  with  dilute  nitric  acid, 
and  afterward  with  salts  of  tartar,  and  finally  clean  and 
polish  the  plate  with  rotten-stone  and  alcohol.  Some  old 
plates  that  have  lain  long  in  water  in  which  the  old  develop- 
ing solutions  have  been  thrown  I  have  never  succeeded  in 
cleaning  so  as  to  prevent  fogging  ;  they  are  contaminated  to 
the  backbone. 

The  use  of  gutta-percha  baths,  etc. — Instead  of  these,  use 
glass,  porcelain  or  photographic  ware  baths — the  latter  are 
very  highly  recommended  ;  I  prefer  glass  to  every  other 
material. 

Spots  and  Apertures, 

Opaque  and  transparent  specks  are  the  most  troublesome 
annoyances  in  the  collodion  negative  process,  and  occur  to 
every  photographer  more  or  less.  These  can  be  attributed 
to  various  causes,  but  seldom  for  the  time  being  to  the  right 
cause  ;  that  is,  we  know  in  general  what  will  cause  them, 
but  seldom  what  did  cause  them. 


IMPERFECTIONS  AND  THEIR  REMEDIES.  329 

The  opaque  spots  may  be  caused  in  the  first  place  by  dust 
on  the  surface  of  the  glass  before  the  collodion  is  poured  on. 
The  remedy  is  simple  :  brush  off  the  dust  with  a  broad,  flat 
camel's  hair  pencil  just  before  the  collodion  is  applied. 

Secondly. —  Opaque  spots  may  be  caused  by  dust  on  the 
surface  of  the  collodion  ;  this  dust  may  be  deposited  either 
from  the  bath  itself,  previous  to  immersion  in  the  bath,  or 
in  the  camera  during  exposure.  That  which  is  deposited 
either  before  or  after  immersion,  are  the  organic  substances 
in  a  state  of  very  minute  division  floating  about  in  the  at- 
mosphere or  set  in  motion  within  the  camera  by  the  agita- 
tion produced  with  the  plate-holder.  This  is  perhaps  the 
most  fruitful  source  of  trouble,  which  is  of  two  kinds,  opaque 
and  transparent  spots.  The  particles  of  dust  attach  them- 
selves to  the  collodion  with  different  degrees  of  tenacity  ; 
where  the  tenacity  is  small,  the  dust  is  washed  off  in  the 
different  manipulations  of  developing  and  fixing,  and  the 
consequence  is  the  production  of  transparent  specks  ;  on 
the  contrary,  where  the  tenacity  is  great,  opaque  spots  are 
the  result ;  for  the  particles  remain  imbedded  after  the  final 
washing.  If  the  dust  be  deposited  from  the  bath  itself,  it 
may  arise  either  from  organic  materials,  in  the  atmos- 
phere or  from  an  excess  of  iodide  of  silver  in  the  bath,  in 
the  form  of  the  violet-colored  deposit  found  at  the  bottom 
or  on  the  walls  of  the  bath.  The  remedy  is,  in  the  first  case, 
to  keep  your  room-floors  moist,  and  your  camera  perfectly 
free  from  this  enemy  by  dusting  and  sponging.  In  the  sec- 
ond place,  the  insoluble  deposit  in  the  bath  is  separated  by 
filtration  ;  the  bath,  too,  is  thoroughly  cleaned  by  a  sponge 
tied  to  the  end  of  a  rod,  which  can  be  made  to  enter  into  the 
angular  spaces  in  which  the  dust  is  deposited. 

Thirdly. — Another  source  of  this  trouble  with  opaque 
spots  is  to  be  found  in  the  collodion,  which  contains  some- 
times undissolved  pyroxyline  in  the  form  both  of  dust  and 
fibres,  or  in  fine  organic  dust  from  impure  sources  of  mani- 
pulation. To  remedy  the  evil,  allow  the  collodion  to  settle 
thoroughly  and  use  only  the  clear  supernatant  part. 

Transparent  Spots. 

These  are  of  much  more  frequent  occurrence  than  opaque 
spots.  They  may  arise,  in  the  first  place,  from  undissolved 
particles  of  the  iodides  in  the  ether  and  alcohol  of  the  col- 
lodion ;  this  is  particularly  the  case  with  iodide  of  potassium 
in  anhydrous  alcohol ;  these  afterward  become  dissolved  in 


330  IMPERFECTIONS  AND  THEIR  REMEDIES. 

the  subsequent  operations.  The  remedy  is  a  drop  or  two  of 
water,  or  of  diluted  alcohol,  or  of  bromide  of  ammonium. 

As  remarked  in  reference  to  opaque  spots,  particles  of 
dust  in  the  camera  or  of  the  insoluble  iodide  of  silver  in  the 
bath,  adhering  to  the  surface  of  the  collodion,  produce  specks, 
both  opaque  and  transparent.  The  transparent  ones  result 
from  the  fact  that,  during  exposure,  and  the  dust  particles 
being  opaque,  they  prevent  the  rays  of  light  from  acting 
actinically  on  the  collodion  film  beneath,  and  then,  being 
washed  off  in  the  subsequent  manipulations  of  development, 
fixing,  intensifying,  and  washing,  they  leave  the  collodion  in 
those  parts  to  the  mercy  of  the  fixing  solutions,  which  ren- 
der them  quite  transparent.  The  remedy  is  to  keep  the  cam- 
era and  the  room  free  from  dust,  and  the  bath  from  insoluble 
particles  of  the  iodide  of  silver  or  organic  materials.  If  the 
bath  is  the  cause,  the  trouble  may  be  avoided  by  keeping  the 
plate  in  motion  during  sensitization. 

Another  cause  of  transparent  spots,  and  probably  a  very 
frequent  one,  is  to  be  attributed  to  a  crystalline  deposit  of 
iodo-nitrate  of  silver,  which,  as  the  bath  becomes  weaker,  is 
precipitated  in  a  crystalline  form  on  the  surface  of  the  collo- 
dion film.  This  form  of  deposit  occurs  with  an  old  bath. 
Its  remedy  is  to  precipitate  it  out  of  the  bath  by  adding 
water,  and  then  by  filtration.  Then  for  every  ounce  of  water 
thus  added  pour  in  after  filtration  the  same  amount  of  a  ni- 
trate of  silver  solution  to  take  its  place. 

When  the  bath  is  the  cause  of  transparent  spots,  a  small 
quantity  of  a  solution  of  chloride  of  sodium  (common  salt) 
thrown  in  is  found  to  be  of  great  benefit.  Chloride  of  silver 
and  nitrate  of  soda  are  formed  by  double  decomposition; 
the  insoluble  chloride  probably  carries  down  with  it  the  dust 
or  particles  which  are  the  cause  of  the  trouble,  or  the  nitrate 
of  soda  dissolves  them.  I  am  not  able  to  say  what  is  the 
true  explanation.  After  filtration  the  bath  is  raised  to  the 
proper  strength,  when  it  will  be  found  to  be  free  from  the  evil. 

Midges  and  Undulating  Lines, 
These  are  caused  by  the  too  great  consistency  of  the  col- 
lodion, and  are  found  in  the  direction  of  the  current  of  the 
collodion.  The  remedy  is  to  add  sufficient  ether  to  cause 
the  collodion  to  flow  smoothly,  easily,  and  uniformly  over 
the  plate.  The  mottled  appearance  sometimes  apparent  on 
a  collodion  film,  as  if  covered  with  flocks  of  wool,  is  owing 
also  to  the  thickness  of  the  collodion,  and  the  evil  is  remedied 
in  the  same  manner  as  the  ridges. 


IMPERFECTIONS  AND  THEIR  REMEDIES. 


331 


Streaks  and  Stains. 

Streaks  may  arise  from  an  irregularity  in  the  immersion 
of  the  plate  in  the  silver  bath,  or  in  withdrawing  it;  the 
plate  has  to  be  immersed  or  withdrawn  without  any  stop- 
ping. Streaks  and  stains  are  produced,  too,  by  the  him  of 
dust  swimming  on  the  surface  of  the  vertical  bath,  which  is 
carried  down  on  the  collodion  when  the  plate  is  immersed. 

They  arise,  secondly,  from  the  irregular  flowing  of  the 
developing  solution  ;  the  remedy  is  to  use  the  gutta-percha 
developing  dish  already  recommended  for  such  purposes. 
Another  remedy  may  be  a  proper  quantity  of  alcohol  added 
to  the  developer,  if  there  happen  to  be  a  sort  of  greasiness 
or  repulsion  in  the  collodion  film  to  the  developing  solution 
as  it  flows  along. 

The  part  upon  which  the  developer  first  comes  in  contact 
with  the  collodion  film  almost  invariably  exhibits  a  streak 
around  a  denuded  part,  as  if  the  developer  had  swept  off  the 
latent  image  in  that  part.  The  remedy  is  the  developing 
dish,  by  which  the  developer  acts  with  little  or  no  moment- 
um greater  at  one  part  than  at  another. 

A  sort  of  fortification  system  of  stains  and  streaks  arises 
from  the  want  of  cleanness  of  the  corners  of  the  plate-shield, 
from  an  inferior  quality  of  collodion,  from  the  unequal  dry- 
ness of  the  film  before  immersion  in  the  silver  bath,  as  well 
as  from  a  too  great  and  irregular  dryness  of  the  film  after 
exposure  and  before  development.  The  remedies  are  self- 
apparent;  avoid  the  causes. 

Stains  of  a  blue  color  arise  from  imperfect  washing  be- 
tween developing  and  fixing. 

Feebleness  of  the  Image,  or  deficiency  of  Contrast. 

A  new  collodion  will  very  frequently  be  one  cause  of  this 
trouble — the  materials  are  not  yet  ripe.  As  a  remedy,  add 
old  collodion,  or  wait  for  a  few  days,  until  the  collodion  is 
sufficiently  decomposed. 

Over-exposure  is  another  and  very  frequent  cause  of  a 
feeble  contrast  in  the  picture.    All  the  parts  are  developed  >> 
simultaneously,  and  too  much  deposit  of  reduced  silver  is 
the  result  all  over  the  picture.    A  shorter  exposure  is  the 
remedy. 

Too  intense  a  developer,  or  a  developer  continued  too  long, 
fogs  the  picture  and  weakens  the  contrast. 

Imperfect  lighting  is  a  third  cause,  in  which  the  light  is 
either  small  in  quantity,  or  diminished  in  intensity  by  reason 
of  peculiarities  in  the  atmosphere. 


332 


IMPERFECTIONS  AND  THEIR  REMEDIES. 


Harshness ',  or  Excess  of  Contrast. 
Under-exposure,  a  too  acid  bath,  a  too  acid  developer,  un- 
der-development,  an  old  and  insensitive  collodion :  all  these 
will  produce  pictures  of  mere  black  and  white  ;  the  interme- 
diate tones  are  totally  wanting.  The  remedy  is  apparent ; 
use  it  as  the  case  may  be. 

Imperfect  Definition. 

This  may  be  caused  by  the  want  of  coincidence  in  the  chemi- 
cal and  luminous  focus.  See  that  the  surface  of  the  ground 
glass  and  that  of  the  inserted  plate  have  exactly  the  same  dis- 
tance from  the  back  lens,  and  correct  this  evil  according  to 
rules  already  laid  down. 

The  want  of  sharpness  may  arise  from  careless  focussing, 
from  the  mobility  of  the  sitter  during  exposure,  from  a  change 
of  position  in  the  camera  when  inserting  the  sensitized  plate, 
or,  in  fine,  from  a  bad  lens.  The  remedy  in  every  one  of  these 
cases  is  obvious,  excepting  perhaps  in  the  last ;  for  the  pho- 
tographer may  not  always  be  in  a  condition  to  get  a  better 
lens.  The  only  and  most  advisable  remedy  in  this  case  is  to 
close  his  gallery  and  feign  sickness,  until  the  return  of  the 
Express  from  the  city,  rather  than  lose  his  reputation  or  gain 
a  bad  one.  In  many  cases  a  microscope  is  employed  in  very 
refined  focussing,  especially  in  copying. 

Polarization. 

This  trouble  does  not  occur  very  frequently;  it  is  made 
manifest  by  the  redness  which  the  high-lights  are  wont  to 
assume  during  development,  when  the  exposure  has  been 
either  too  long  or  the  light  too  brilliant,  as  in  the  copying 
process  by  the  direct  rays  of  the  sun.  This  evil  can  be 
remedied  by  avoiding  the  causes,  or  by  the  .use  of  a  bromo- 
iodized  collodion,  or  of  citric  acid  in  the  developer. 

Tender  and  Rotten  Films. 

These  occur  generally  in  collodion  of  a  certain  make, 
owing  to  the  peculiar  nature  of  the  pyroxyline,  or  the  relative 
quantity  of  alcohol  and  ether.  The  defect  may  arise,  how- 
ever, by  immersing  the  plate  too  quickly  into  the  silver  bath 
before  the  film  has  set ;  also  by  immersing  the  plate  when 
the  film  is  too  dry,  in  which  case  it  cracks  and  splits  up  in 
the  development. 

There  is  no  remedy  for  a  rotten  film ;  but  a  tender  or 
structureless  film  can  oe  retained  on  the  glass  by  first  filing 
the  edges  as  recommended,  and  then  by  careful  manipula- 
tions in  the  various  operations  of  developing,  fixing,  and 
washing. 


IMPERFECTIONS  AND  THEIR  REMEDIES.  333 


Imperfections  in  Paper  Prints, 
These  are  to  be  attributed  to  defects  in. the  paper  ;  to  im- 
perfect albumenizing  and  salting  ;  to  defective  sensitizing  ; 
to  defects  in  the  printing  or  in  the  negative  ;  to  imperfect 
washing^  previous  to  toning  /  to  defective  toning  /  to  defect- 
ive fixing y  to  stains  of  various  kinds  /  mealiness  on  the 
print. 

Defects  in  the  Paper. 
A  defective  piece  of  paper  must  always  be  rejected  at 
once.  By  regarding  the  paper  by  transmitted  light,  very 
frequently  imperfections  in  the  substance  of  the  material  can 
be  descried,  which  otherwise  would  escape  observation.  Par- 
ticles of  inorganic  matter,  such  as  lime,  the  oxide  of  iron,  etc., 
may  be  found  in  the  substance,  which  in  the  various  stages 
of  the  printing  operation  become  manifest  by  decomposi- 
tion. In  choosing  paper,  where  you  can  make  the  selection, 
examine  each  sheet  separately  for  mechanical  defects  both  of 
structure  and  of  contamination,  and  reject  whatever  is  in 
any  way  defective. 

Imperfect  Albumenizing  and  Salting. 
The  albumenizing  and  salting  require  careful  and  neat 
management.  If  the  albumen  is  not  very  thoroughly  broken 
up,  it  will  assuredly  produce  irregularities  in  the  albumeniz- 
ing. The  salting  materials  must  be  mixed  up  at  the  same 
time  with  the  albumen,  but  after  solution  in  a  small  quantity 
of  water  ;  otherwise  particles  of  the  salt  will  remain  undis- 
solved and  give  a  spotted  appearance  in  the  printing.  Use 
the  albumen  while  fresh.  See  that  the  surface  is  not  com- 
posed of  bubbles  ;  where  these  exist  you  will  have  a  marbled 
or  oolitic  appearance  on  your  print.  If  the  paper  exhibits 
such  minute  bubbles  when  removed  from  the  salting  solu- 
tion, break  these  bubbles  all  up  with  a  clean  feather  or  soft 
sponge,  and  float  the  paper  again  until  the  film  is  uniform. 
The  amount  of  salting  ought  to  bear  a  relation  of  equiva- 
lents with  the  silver  solution  used  subsequently. 

Defective  Sensitizing. 
Filter  the  silver  solution  before  use,  or  at  least  remove  all 
particles  of  dust  or  oxide  from  its  surface,  otherwise  your 
prints  will  be  spotted  and  frequently  covered  with  fortifica- 
tions. A  marbled  appearance  is  caused  by  a  weak  silver  so- 
lution, or  too  short  a  time  of  floating.  It  may  arise  from 
defects  in  the  albumenizing,  as  just  referred  to.  In  quick 
floating  the  solution  must  be  very  strong.    In  some  cases  the 


334  IMPERFECTIONS  AND  THEIR  REMEDIES. 


solution  seems  to  be  rejected  from  the  surface  of  the  albu- 
men ;  rub  over  the  solution  with  a  tuft  of  cotton ;  float  again, 
and  the  trouble  will  be  overcome. 

Defects  in  the  Printing  or  in  the  Negative, 
A  weak  negative  will  inevitably  produce  a  toeak  print. 
Weak  prints,  too,  are  the  result  of  too  dilute  a  silver  solu- 
tion. Bronzing  arises  frequently  from  a  want  of  true  rela- 
tion between  the  lights  and  shades  in  the  negative.  An  in- 
tensified ambrotype  used  as  a  negative  will  produce  a  bronzed 
picture.  Thus  under-exposure  and  over-development  are  the 
causes  of  bronzing. 

A  harsh  print  proceeds  also  from  under-exposure  and  over- 
development  in  the  negative  ;  there  is  a  want  of  middle-tone — 
the  picture  is  all  black  and  white. 

Many  prints  are  spoiled  in  the  act  of  printing  by  extreme 
carelessness.  Watch  the  operation  ;  the  two  guides  of  suc- 
cess are  :  Print  as  long  as  the  high-lights  are  perfectly  white, 
and  bronzing  has  not  yet  commenced.  The  impression  of  a 
perspiring  finger  on  the  sensitive  film,  as  well  as  many  other 
similar  organic  contaminations,  also  give  rise  to  bronzing. 

Imperfect  Washing  previous  to  Toning. 

The  print,  when  removed  from  the  printing-frame,  contains 
nitrate  of  silver  and  nitrate  of  the  alkalies  used  in  the  salt- 
ing solutions,  albuminate  of  silver,  chloride  of  silver ;  the 
latter  salt  has  been  partly  acted  upon  by  light  so  as  to  form 
the  picture,  and  another  part  has  not  been  changed.  The 
nitrates  must  all  be  removed  by  careful  washing  in  several 
waters  before  the  toning  is  commenced,  otherwise  the  toning 
loill  be  slow  and  imperfect. 

The  operation  of  washing  must  take  place  soon  after 
printing  and  immediately  before  toning,  in  order  to  secure 
a  good  and  quick  tone. 

Defective  Toning. 

This  imperfection  may  arise  from  contaminations  intro- 
duced into  the  toning  solution  by  imperfectly  washed  prints ; 
the  gold  solution  becomes  thereby  decomposed  and  incapable 
of  toning  the  printed  film.  The  defect  may  arise  from  im- 
pure chloride  of  gold ;  from  an  acid  condition  of  the  toning 
solution  ;  from  bad  paper  ;  from  the  lowness  of  the  temper- 
ature ;  from  an  excess  of  elevation  of  temperature.  The 
imperfections  of  toning  are  : 

A  red  tone  after  fixing ;  this  is  owing  to  an  insufficiency 
of  toning. 


IMPERFECTIONS  AND  THEIR  REMEDIES. 


335 


A  blue  tone  after  fixing  ;  this  is  owing  to  an  excess  of  ton- 
ing ;  or  to  an  acid  toning  solution. 

A  yellow  tone  in  the  whites  after  fixing  ;  this  may  be  ow- 
ing to  imperfect  washing,  imperfect  toning,  imperfect  fixing, 
dirty  fingers,  introduction  of  hyposulphite  of  soda  into  the 
toning  solution,  or  upon  the  prints.  The  defect  in  question 
may  arise  also  from  the  decomposition  of  the  gold  in  pathces, 
for  want  of  uniform  mixture  before  the  prints  are  introduced. 

Defective  Fixing. 
A  dark  mottled  appearance  in  the  body  of  the  paper  in- 
dicates imperfect  fixing  combined  with  the  action  of  the  light 
on  the  unaltered  chloride  during  fixing.  An  exhausted  hy- 
posulphite bath  may  also  give  rise  to  this  defect.  A  bath 
containing  hydrosulphuric  acid,  or  a  free  acid,  which  will  pro- 
duce the  former,  gives  rise  to  this  dark-gray  mottled  defect. 

A  yellow  tone  in  the  whites  arises  very  frequently  from  sul- 
phurized hyposidphite  stains  of  various  kinds. 

These  are  owing  to  irregular  and  careless  manipulations. 
The  introduction  of  the  fingers  into  the  various  baths,  and 
indiscriminately  from"  one  bath  into  another,  is  the  cause  of 
a  number  of  stains  on  the  prints,  as  well  as  of  abnormal  ac- 
tion of  the  baths  themselves. 

Make  rules  for  yourself,  such  as  the  following,  and  observe 
them  minutely : 

1.  Print  just  to  bronzing,  or  until  the  whites  begin  to  be 
affected. 

2.  Wash  soon  after  printing  in  clean  water  and  clean  pails. 

3.  Move  the  prints  about  in  the  washing  ;  repeat  the  wash- 
ing three  times  ;  two  or  three  minutes'  duration  for  each  is 
enough.    Long  washing  is  injurious. 

4.  The  chloride  of  gold  must  be  pure ;  the  solution  must 
be  neutralized  with  alkalies  or  lime. 

5.  The  toning  solution  must  be  warm — about  100° — and 
well  mixed — and  clean. 

6.  Wash  after  toning  quickly — in  warm  or  hot  water  pref- 
erable— take  care  to  introduce  no  gold  solution  into  the  fix- 
ing solution,  and  vice-versd. 

1.  Move  the  prints  about  in  all  the  solutions,  so  as  to  avoid 
bubbles  and  uneven  action. 

8.  Tone  to  purple  or  incipient  violet. 

9.  Use  fresh  toning  for  a  fresh  batch  of  prints. 

10.  Add  fresh  hyposulphite  every  time  to  the  old  bath, 
or  use  a  fresh  fixing-bath  every  time ;  let  the  bath  be  warm. 


336  IMPERFECTIONS  AND  THEIR  REMEDIES. 

1 1 .  Alcohol  is  an  advantage  in  all  the  solutions  beginning 
with  the  nitrate  of  silver  to  the  hyposulphite  of  soda. 

12.  Wash  very  thoroughly  after  fixing. 

Mealiness  on  the  Print, 

Some  authors  speak  of  this  defect  in  albumen  prints.  It 
is  said  to  proceed  from  paper  that  has  been  long  albumen- 
ized,  or  from  the  paper  itself.  The  remedy  is  to  immerse 
the  prints  in  a  solution  of  two  ounces  of  water  and  eighteen 
grains  of  acetate  of  soda,  and  to  keep  them  in  this  liquid 
for  about  ten  minutes. 

Prints  frequently  appear  as  if  covered  with  snow,  but  the 
surface  is  quite  smooth  and  the  whites  clear ;  this  defect  is 
attributable  to  the  negative,  which  has  been  strengthened  by 
pyrogallic  acid  containing  too  much  nitrate  of  silver.  The 
surface  of  the  negative  becomes  thereby  covered  with  a  pul- 
verulent deposit.  There  is  no  remedy  for  such  a  negative  ; 
there  is  a  remedy,  however,  to  such  a  mode  of  intensifying. 
In  the  first  place,  the  negative  must  contain  the  middle  tones 
before  you  begin  to  intensify ;  secondly,  intensify  slowly, 
which  is  effected  by  adding  only  three  or  four  drops  of  silver 
at  a  time  to  the  pyrogallic  acid,  and  shaking  well  before  use. 


CHAPTER  XLV. 


WEIGHTS  AND  MEASURES. 

Weights  and  capacities  in  England  and  France  are  esti- 
mated from  certain  standard  linear  measurements.  In  Eng- 
land, a  pendulum  vibrating  seconds  of  time  in  a  vacuum,  at 
the  latitude  of  London,  and  at  the  level  of  the  sea,  is  assum- 
ed as  the  standard  of  linear  dimensions;  it  is  39.1393  inches. 
This  is  the  standard,  too,  of  all  our  measurement  of  length, 
capacity,  and  weight  in  the  United  States.  But,  like  the 
English,  we  retain  all  the  old  and  arbitrary  systems  of 
weights  and  measures  ;  whereas  the  French  have  assumed  a 
decimal  system  in  all  their  measurements  that  merits  the 
highest  praise  and  imitation.  The  linear  standard  of  the 
French,  from  which  they  derive  all  other  measurements,  is 
called  a  metre.  It  is  the  ten-millionth  part  of  a  quarter  of 
the  earth's  meridian,  and  measures  39.371  inches.  The  metre 
is  divisible  decimally  in  both  directions. 

The  connecting  link  'between  the  English  linear  unit  and 
their  measures  of  capacity  and  weight  are  as  follows  : 

A  cubic  inch  of  distilled  water  weighed  in  air  with  brass 
weights  at  a  temperature  of  62°  Fahr.,  the  barometer  stand- 
ing at  30  inches,  is  equal  to  two  hundred  and  fifty-two  grains 
and  four  hundred  and  fifty-eight  one  thousandth  parts  of  a 
grain  ;  of  such  grains  5760  are  required  to  make  the  impe- 
rial standard  troy  or  apothecaries' pound  ;  and  7000  of  such 
grains  make  the  commercial  or  avoirdupois  pound.  The 
imperial  gallon  has  a  capacity  of  277.274  cubic  inches  ;  and 
a  gallon  of  distilled  water,  as  above,  weighs  10  pounds 
avoirdupois,  or  70,000  grains. 

The  connecting  link  between  the  French  linear  unit  and 
their  measures  of  weight  and  capacity,  are  as  follows  : 

A  cubic  centimetre  of  distilled  water,  at  its  maximum 
density,  at  the  temperature  of  39.5°  Fahrenheit,  is  the  unit 
of  weights  and  is  called  a  gramme^  which  is  divided  deci- 
mally above  and  below. 

A  cubic  decimetre  is  called  a  litre,  which  is  the  unit  of  the 
measures  of  capacity,  and  divisible  decimally. 
15 


338 


WEIGHTS  AND  MEASURES. 


Comparison  of  Weights  and  Measures. 

Apothecaries1  Weight. 


20  grains 
60  grains 
480  grains 
5760  grains 


3  scruples  == 
8  drachms  = 
12  ounces  — 


1  grain 
1  scruple 
1  drachm 
1  ounce 
1  pound 


French  gramme. 
=  0.0647 
=  1.295 
=  3.885 
=  31.08 
£=  372.96 


Symbols. 

Grain  =±  gr.    Scruple  =  3 .    Drachm  =  3  .    Ounce  =  §  .    Pound  =  lb 


Apothecaries1  Measure  of  Capacity.    (United  States.) 

1  fluid  drachm. 
=    1  fluid  ounce. 
=    1  pint. 
=    1  gallon. 


60  minims  sj= 

480  minims  —    8  fluid  drachms 

7680  minims  =16  fluid  ounces 

61,440  minims  =    8  pints 


Avoirdupois  Weight. 


16  drachms 
16  ounces 
112  pounds 
20  hundred  weight 


French  gramme. 
1  drachm    ==  1.77 


1  ounce 
1  pound 

1  hundred  weight 
1  ton 


28.328 
453.25 


1  drachm  — 

1  ounce  = 

1  pound  = 

1  hundred  weight  as 

1  ton  = 


Apothecaries1  grains. 

—  27.34375 
=  437.5 
=  7000. 
784000. 
15680000. 


Apothecaries'  ounce 
Avoirdupois  ounce 
United  States  pint 
Imperial  or  British  pint 
United  States  gallon 
Imperial  or  British  gallon 


—  480  grains, 
as  437.5  grains. 
=    16  fluid  ounces. 
=    20  fluid  ounces. 

=  128  fluid  ounces.  =  8  pounds  ayoirdupoi3. 
=  160  fluid  ounces  =  10     "  " 


Weight  of  Water  at  62°  and  Capacity  of : 


1  gallon  (Imperial) 
1  gallon  (U.  S.) 
1  quart  (Imperial) 
1  quart  (U.  S.) 
1  pint  (Imperial) 
1  pint  (U.  S.) 
16  fluid  ounces 
1  fluid  ounce 
1  fluid  drachm 
1  minim 


Cubic  inches. 
:  277.274  = 
:  231.000  = 
:  69.318  = 
:  57.750  s= 
:  34.659  = 
:  28.875  = 
:  28.875  = 
1.732  = 
:  0.216  = 
:      0.0336  = 


Grains. 
70000. 
56000. 
17500. 
14000. 
8750. 
7000. 
7000. 
437.5 
54.7 
0.91 


WEIGHTS  AND  MEASURES. 


339 


French  Measures  of  Length, 

English  inches. 
Millimetre      ==  .03937 
Centimetre      =  .39371 
Decimetre      =s  3.93708 
Metre  =  39.37079 

Decametre      ==  393.70788 
Hectometre     =  3937.0788 
Kilometre      =  39370.788 
Myriametre     s=  393707.88 

French  Weights. 

Equivalents  in  Grains. 

Milligramme,   .0154 

Centigramme,  .    .        ....  .1543 

Decigramme,         .    .    .    .    .  1.5434 

Gramme,   15.434 

Decagramme,   154.340 

Hectogramme,   1543.402 

Kilogramme,   15434.023 

Myriogramme   154340.234 

A  gramme  of  water  =  1  cubic  centimetre  =  15.43  grains  =  17  minims. 
1000  grammes  of  water  =  1  litre  =  1  kilogramme  =  15434.023  grains  = 
2  lb.  3.27  oz. 

French  Liquid  Measures.    United  States  Liquid  Measures. 
Cubic  inches. 

Millilitre,   ....  .0610    16.2318  minims. 

Centilitre,    .    .    .  .6103    2.7052  fl.  drachms. 

Decilitre,   .    <    .    .  6.1028    3.3816  fl.  ounces. 

Litre,   61.028    2.1135  pints. 

Decalitre,.    .    .    .       610.280    2.6419  gallons. 

Hectolitre,    .    .    .       6102.80    26.4190  " 

Kilolitre,   ....    61028.0    264.1900  " 

Myrialitre,    .    .    .    610280.        .    .  7   .    .     2641.9000  " 


CHAPTER  XL VI. 


COMPARISON    OF    THERMOMETRY    INDICATIONS    ON  THE 
PRINCIPAL   THERMOMETERS    IN  USE. 

Thermometers  are  instruments  for  ascertaining  the  tem- 
perature of  bodies,  whether  liquid,  solid,  or  gaseous.  The 
principal  thermometers  in  use  are  :  the  Centigrade,  which 
is  used  principally  in  France ;  Reaumur's  thermometer,  of 
more  especial  use  in  Germany ;  and  Fahrenheit's  thermome- 
ter, used  more  especially  in  Great  Britain  and  the  United 
States. 

The  temperature  of  boiling  water  is 
100°  on  the  Centigrade  scale. 

80°  on  Reaumur's  scale. 
212°  on  Fahrenheit's  scale. 

The  freezing  point  of  water  is  indicated  by 
0°  on  the  Centigrade  scale. 
0°  on  Reaumur's  scale. 
32°  on  Fahrenheit's  scale. 

The  number  of  degrees  between  the  freezing  point  and  the  boiling  point  is 
100°  on  the  Centigrade  scale. 

80°  on  Reaumur's  scale. 
180°  on  Fahrenheit's  scale. 

To  reduce  Centigrade  degrees  to  those  of  Reaumur. 
Rule :  Multiply  by  4  and  divide  by  5. 
To  reduce  Reaumur's  degrees  to  those  of  the  Centigrade. 
Rule :  Multiply  by  5  and  divide  by  4. 
To  reduce  Centigrade  degrees  to  those  of  Fahrenheit. 
Rule :  Multiply  by  9,  divide  by  5,  and  add  32  to  the  quotient. 
To  reduce  Fahrenheit's  degrees  to  those  of  the  Centigrade. 
Rule :  Subtract  32,  multiply  the  difference  by  5,  and  divide  by  9. 
To  reduce  Reaumur's  degrees  to  those  of  Fahrenheit. 
Rule  :  Multiply  by  9,  divide  by  4,  and  add  32  to  the  quotient. 
To  reduce  Fahrenheit1  s  degrees  to  those  of  Reaumur. 
Rule  :  Subtract  32,  multiply  the  difference  by  4,  and  divide  by  9. 


COMPARISON  OF  THERMOMETRY  INDICATIONS.  341 


Table  of  tlie  corresponding  degrees  on  the  Scales  of  Fahren- 
heit, Reaumur,  and  the  Centigrade. 


Fahrenheit 

Reaumur. 

Centigrade. 

Boiling  point,  212 

80 

100 

203 

76 

95 

194 

72 

90 

185 

68 

85 

176 

64 

80 

167 

60 

75 

158 

56 

70 

149 

52 

65 

140 

48 

60 

131 

44 

55 

122 

40 

50 

113 

36 

45 

104 

32 

40 

95 

28 

35 

86 

24 

30 

77 

20 

25 

68 

16 

20 

59 

12 

15 

50 

8 

10 

41 

4 

5 

32 

0 

0 

23 

—4 

—5 

14 

—8 

—10 

5 

—12 

—15 

—4 

—16 

—20 

—13 

—20 

—25 

—22 

—24 

—30 

—31 

—28 

—35 

—40 

—32 

—40 

All  the  intermediate  indications  can  be  obtained  by  the 
use  of  the  preceding  rules. 


CHAPTER  XLVIL 


COMPARISON   OF   HYDROMETRIC   AND    SPECIFIC  GRAVITY 
INDICATIONS. 

The  specific  gravity  of  a  body  is  the  comparison  of  the 
weight  of  a  given  bulk  of  the  said  substance  with  that  of  an 
equal  bulk  of  distilled  water  at  62°  Fahrenheit.  Gases  are 
compared,  either  with  air  as  the  standard  or  with  distilled 
water. 

The  specific  gravity  of  a  body  is  taken  by  special  instru- 
ments for  this  purpose ;  some  of  these  instruments  are  de- 
nominated Hydrometers,  and  give  arbitrary  indications, 
which  have  to  be  reduced  afterward  in  terms  of  specific 
gravity. 

Baume's  Hydrometers  are  in  extensive  use  in  France,  and 
TwaddelPs  Hydrometer  in  England.  Baume  has  two  Hy- 
drometers :  one  for  liquids  heavier  than  water,  and  one  for 
liquids  lighter  than  water. 


For  Liquids  Heavier  than  Water.  Baume. 


Beg. 

Sp.  Grav. 

Beg. 

JSp.  Grav. 

Beg. 

Bp.  Grav. 

Beg. 

Sp.  Grav. 

0  .. 

. .  1.000 

20  . 

...  1.152 

40  . , 

.  .  1.357 

60  . 

...  1.652 

1 

. .  1.007 

21  . 

. . .  1.160 

41 

..  1.369 

61  . 

. ..  1.670 , 

2  .. 

. .  1.013 

22  . 

. ..  1.169 

42  . 

..  1.381 

62  . 

.  . .  1.689 

3  .. 

. .  1.020  - 

-   23  . 

...  1.178 

43  . 

..  1.395 

63  . 

. . .  1.708 

4 

. .  1.027  3j 

t  24  . 

...  1.188 

44  . 

. .  1.407 

64  . 

. . .  1.727 

5  .  . 

. .  1.034  £ 

25  . 

...  1.197 

45  . 

..  1.420 

65  . 

. . .  1.747 

6 

. .  1.041 

26  . 

. . .  1.206 

46  . 

. . .  1.434 

66  . 

. . .  1.767 

7 .. 

. .  1.048 

27  . 

...  1.216 

47  . 

.  .  1.448 

67  . 

...  1.788 

8  .. 

..  1.056 

28  . 

. ..  1.225 

48  . 

. . .  1.462 

68  . 

. . .  1.809 

9  .. 

..  1.063 

29  . 

. . .  1.235 

49  . 

. . .  1.476 

69  . 

. ..  1.831 

10 

. .  1.070 

30  . 

. . .  1.245 

50  . 

. . .  1.490 

70  . 

. ..  1.854 

11 .. 

..  1.078 

31  . 

. . .  1.256 

51  . 

. ..  1.505 

71  . 

. . .  1.877 

12  .. 

. .  1.085 

32  . 

. ..  1.267 

52  . 

. . .  1.520 

72  . 

. . .  1.900 

13  .. 

. .  1.094 

33  . 

. . .  1.277 

53  . 

. ..  1.535 

73  . 

. . .  1.924 

14  . . 

. .  1.101 

34  . 

. 1.288 

54  . 

.  .  .  1.551 

74  . 

. . .  1.949 

15  .. 

..  1.109 

35  . 

.  ..  1.299 

55  . 

...  1.567 

75  . 

. . .  1.974 

16 

. .  1.118 

36  . 

...  1.310 

56  . 

...  1.583 

76  . 

. . .  2.000 

17 

1.126 

37  , 

. ..  1.321 

57  . 

.  .  .  1.600 

18 

..  1.134 

38  . 

...  1.333 

58  . 

. ..  1.617 

19 

. .  1.143 

39  . 

. . .  1.345 

59  . 

. . .  1.634 

HYDEOMETEIC  INDICATIONS. 


343 


For  Liquids  Lighter  than  Water.  Baume. 


Deg. 

Sp.  Grav. 

Deg. 

Sp.  Grav. 

Leg. 

Sp.  Grav. 

Leg. 

Sp.  Grav. 

10  .. 

1.000 

23  . 

...  0.918 

36  . 

.  .  0.849 

49  . 

. . .  0.789 

11  . . 

. .  0.993 

24  . 

..  0.913 

37  . 

..  0.844 

50  . 

. . .  0.785 

12  . . 

. .  0.987 

25  . 

. . .  0.907 

38  . 

. .  0.839 

51  . 

. . .  0.781 

13  .  . 

.  .  0.980 

26  . 

. .  0.901 

39  . 

. .  0.834 

52  . 

. . .  0.777 

14  .  . 

.  .  0.973 

27  . 

.  .  0.896 

40  . 

.  .  0.830 

53  . 

. . .  0.773 

15  .  . 

.  .  0.967 

28  . 

. .  0.890 

41  . 

. .  0.825 

54  . 

. . .  0.768 

1G  .  , 

.  .  0.960 

29  . 

. . .  0.885 

42  . 

. .  0.820 

55  . 

. . .  0.764 

17  .. 

.  .  0.954 

30  . 

. ..  0.880 

43  . 

.  .  0.816 

56  . 

. . .  0.760 

18  .. 

. .  0.948 

31  . 

. .  0.874 

44  . 

. ..  0.811 

57  . 

. . .  0.757 

19  .. 

. .  0.942 

32  . 

. . .  0.869 

45  . 

. . .  0.807 

58  . 

. .  .  0.753 

20  ,  . 

..  0.936 

33  . 

. .  0.864  - 

46  . 

. . .  0.802 

59  . 

. . .  0.749 

21  .. 

..  0.930 

34  . 

. . .  0.859 

47  . 

. .  0.798 

60  . 

. . .  0.745 

22  .. 

. .  0.924 

35  . 

. . .  0.854 

48  . 

. . .  0.794 

61  . 

. . .  0.741 

TivaddelVs  Hydrometer. 

The  degrees  on  Twaddell  are  converted  into  equivalent 
specific  gravities  by  multiplying  them  by  5  and  adding 
1000;  then  mark  oft'  three  figures  as  decimals. 


Leg. 

Sp.  Grav. 

Leg. 

Sp.  Grav. 

Leg. 

Sp.  Grav. 

Leg. 

Sp.  Grav 

1  . 

. .  1.005 

8  . 

...  1.040 

15  .. 

..  1.075 

22  . 

. .  1.110 

2  . 

. . .  1.010 

9  . 

. . .  1.045 

16  .  . 

. .  1.080 

23  . 

..  1.115 

3  . 

. .  1.015 

10  . 

. . .  1.050 

17  .. 

.  .  1.085 

24  . 

..  1.120 

4  . 

. ..  1.020 

11  . 

. .  1.055 

18 

. .  1.090 

25  . 

.  .  1.125 

5  . 

. ..  1.025 

12  . 

.  . .  1.060 

19  .  . 

. .  1.095 

26  . 

..  1.130 

6  . 

. .  1.030 

13  . 

.  .  .  1.065 

20  . . 

. .  1.100 

27  . 

.  .  1.135 

*  . 

. . .  1.035 

14  . 

. . .  1.070 

21 

..  1.105 

28  . 

...  1.140 

CHAPTER  XLVIII. 


TABLE    OF   THE    ELEMENTS    OF   MATTER,    WITH  THEIR 
SYMBOLS  AND  CHEMICAL  EQUIVALENTS. 


,  Elements.  Symbol. 

Chem. 
Eq^u/vo  . 

Aluminum,  s  „ . . 

..Al. 

14 

Antimony,  (Stibium,). . 

.Sb. 

129 

.As. 

•  15 

Ba. 

69 

Bi. 

213 

B. 

11 

Br. 

IS 

Cd. 

56 

Cse. 

123 

,0a. 

20 

0. 

6 

Ce. 

46 

01. 

36 

Or. 

26 

Co. 

30 

Columbium,  (Tantalum,).  .Ta. 

184 

Cu. 

32 

Didymium,  

Di. 

48 

,Er. 

? 

F. 

19 

G. 

V 

Au. 

197 

Hydrogen,  

H. 

1 

U. 

T 

126 

Ir. 

99 

Iron,  (Ferrum,)  

.Fe. 

28 

La. 

44 

.Pb. 

104 

Lithium,  

Li. 

1 

Magnesium,  

Manganese,  

.Mg. 

12 

,Mn. 

28 

Mercury,  (Hydrargyrum, 

)Hg. 

100 

Elements.  Symbol. 

Chcm. 

TP.     A m 
a.  ww* 

Mo. 

38 

Nickel,  

.  Mi. 

30 

.  ,Nb. 

Nitrogen,  

N. 

14 

,  No. 

Osmium,  

,  ,0s. 

100 

0. 

8 

,Pd. 

54 

.  Pe. 

.  P. 

32 

Pt. 

99 

Potassium,  (Kalium,). . 

..K. 

39 

,  ,Ro. 

52 

Rubidium,  

Rb. 

85 

,  Ru. 

52 

Selenium,  

,  Se. 

40 

Si. 

22 

..Ag. 

108 

,  Na. 

23 

.  Sr.; 

44 

.  S. 

16 

.  Te. 

64 

Tb. 

? 

Th. 

60 

Sn. 

59 

Tungsten  (Wolfram,). . 

Ti. 

24 

..W. 

92 

U. 

60 

V. 

68 

Y. 

32 

Zn. 

32 

Zr. 

34 

The  Elements  printed  in  italics  are  the  Metalloids;  the 
rest  are  the  Metals. 


I1STDEX. 


A 

Aberration,  chromatic,  34 ;  spherical,  34. 

Aberration,  to  ascertain  whether  corrected 
for  chromatic,  3T,  38,  39. 

Aberration,  to  ascertain  whether  corrected 
for  spherical,  37. 

Acetate  of  silver,  112. 

Acetate  of  soda,  104,  111,  112,  190 ;  pro- 
duces vigorous  pictures,  111. 

Aceto-nitrate  of  silver,  (formula  for,)  235, 
239,  240,  241. 

Achromatic  lenses,  40. 

Acid,  acetic,  103,  111 ;  glacial,  104  ;  checks 
reduction,  104 ;  gives  sensitiveness,  104. 

Acid,  citric,  preparation  of,  105,  106 ;  uses 
of,  10T. 

Acids,  in  developing  solutions,  102 ;  as  re- 
tarders  of  development,  102, 103. 

Acid,  formic,  a  reducing  agent,  95  ;  prepar- 
ation of,  104 ;  photographic  uses  of, 
105 ;  used  as  developer,  169. 

Acid,  gallic,  a  reducing  agent,  95 ;  symbol 
of,  99 ;  preparation  of,  100 ;  a  devel- 
oper, 237,  239. 

Acid,  hydriodic,  preparation  of,  70. 

Acid,  hydrobromic,  preparation  of,  76. 

Acid,  hydrocyanic,  (prussic,)  preparation 
of,  119. 

Acid,  hydrosulphocyanic,  preparation  of, 
120. 

Acid,  metagallic,  101. 

Acid,  nitric,  a  reducing  agent,  95. 

Acid,  phosphoric,  306. 

Acid,  pyrogallic,  a  reducing  agent,  95 ; 
symbol  of,  99 ;  preparation  of,  101 ; 
a  developer,  146 ;  an  kitensifier,  148. 

Acid,  tannic,  a  reducing  agent,  95 ;  prepar- 
ation of,  99  ;  uses  of,  100  ;  vide  Tannin 
Process,  245 ;  a  developer,  247,  249. 

Acid,  tartaric,  preparation  of,  107;  a  re- 
tarder  of  reduction,  103 ;  printing  with, 
285. 

Actinic  focus,  coincidence  with  luminous, 
39. 

Affinity  of  metals,  95. 

Aguillon,  Francis,  312. 

Alabastrine  positives,  140 ;  alabastrine  so- 
lutions, 140. 

Albumen,  preparation  of,  194 ;  formulas  for 
iodized  albumen,  238,  239,  240,  241, 
243;  albumen-process,  238;  collodio- 
albumen-process,  237,  241 ;  and  bi- 
chromate of  potassa,  299  ;  and  bichro- 
mate of  ammonia,  308. 

Albumenized  paper,  preparation  of,  194. 


Alcohol,  hydrated  oxide  of  ethyle,  56  ;  pre- 
paration of  ether  from,  58 :  prepara- 
tion of,  59,  60. 

Alcoholic  collodion,  19. 

Aldehyde,  111. 

Amber  varnish,  with  chloroform,  137 ;  with 
benzole,  137. 

Ambrotype,  23 ;  how  to  make,  128  to  140. 

Ammonia,  197  ;  bichromate  of,  308. 

Ammonium,  symbol  and  combining  propor- 
tion, 71 ;  chloride  of,  191 ;  iodide  of, 
73 ;  sulphide  of,  125. 

Ammoni-nitrate  of  silver,  formula  for  bath, 
197 ;  albuminous  film  not  injured  by, 
198. 

Angle,  parallactic,  313. 

Aperture  angular,  defined,  40. 

Aperture,  (of  diaphragm,)  relation  between, 

and  opening  of  the  lens,  41. 
Apertures  in  the  collodion  film,  112 ;  cause 

and  remedy,  328,  329. 
Apothecary's  weight,  339. 
Aplanatic  lenses,  40. 

Aqua-tinta  granulation,  289 ;  application 
of,  294,  295. 

Arago,  report  of,  to  the  Chamber  of  Depu- 
ties, 13. 

Arcken,  first  application  of  gun-cotton  by, 
19 ;  and  Fry  published  a  detailed  ac- 
count of  gun-cotton,  51. 

Arrowroot  papers,  preparation  of,  195. 

Asser,  used  transfer  process,  21. 

Asphaltum  in  chloroform,  21 ;  for  black  var- 
nish, 138 ;  dissolves  in  benzine,  291  ; 
properties  of,  298. 

Asphaltotype  of  Nicephore  Niepce,  291. 

Asphalto-photolithographic  process,  297. 

Astronomical  photographers,  320 ;  Society 
confer  medal  on  De  la  Rue,  322. 

Axis,  convergence  of,  314. 

Avoidupois  weight,  338. 


B 

Background,  illustration  of,  30;  various 
plain,  graduated,  pictorial,  31 ;  color- 
ing of,  230. 

Bath,  vertical,  horizontal,  109,  110;  glass, 
porcelain  photographic  ware,  109 ;  pre- 
paration of  the  sensitizing  solutions  for 
collodion  pictures,  110,  111 ;  with  ace- 
tate of  soda  and  acetic  acid,  111 ;  for 
summer,  111 ;  how  to  restore  when 
weak,  111 ;  how  to  treat  the  bath  when 
acid  or  alkaline,  112, 113 ;  the  necessity 


346 


INDEX. 


of  filtering,  113;  to  add  tincture  of 
iodine  to  the  collodion  in  order  to  pro- 
duce acidity  in,  112 ;  take  care  that  no 
actinic  rays  get  to,130 ;  for  paper,  196  ; 
ammonio-nitrate,  197 ;  for  toning,  202. 

Barium,  symbol  and  equivalent,  71 ;  iodide 
of,  71;  chloride  of,  191. 

Barreswil,  attempts  photolithography  first, 
298. 

Beauregard,  Testud  de,  process,  276. 
Beaume,  342. 

Becquerel  on  heliochromy,  323. 

Benzine,  how  to  render  anhydrous,  291,  293. 

Benzoin,  209. . 

Berard's  experiments  with  the  spectrum,  12. 
Berry,  321. 

Bertrand's  new  process  for  positive  print- 
ing, 209. 
Biology,  10. 

Bichromate  of  potassa,  11,  276,  277,  280 ; 
bichromate  of  ammonia,  278,  308. 

Bichromo-photo-lithographic  processes,  299. 

Bichloride  of  mercury,  as  developer,  275 ; 
as  intensifies  169  ;  preparation  of,  125. 

Bitumen  of  Judea,  first  used  by  Niepce,  14. 

Blanchard's  (Valentine)  instantaneous  pro- 
cess, 169 ;  prefers  bromo-iodized  collo- 
dion, 168 ;  strengthened  with  bichlo- 
ride of  mercury,  169. 

Blanquart  Evrard's  intensifying  process 
by  a  second  exposure  to  light,  124; 
bromo-iodizing  solutions  for  printing  by 
development,  263 ;  sensitizing  bath  and 
development,  264. 

Blonde  hair,  coloring  of,  227. 

Black  hair,  coloring  of,  227. 

Blue  drapery,  coloring  of,  227. 

Blue-tone,  owing  to  excess  of  toning,  or  to 
acid  toning,  335. 

Boiled  oil,  in  transfer  varnish,  151. 

Bond,  Messrs.,  320. 

Brewster,  refracting  stereoscope,  312. 

Bromides,  65 ;  bromide  of  silver  sensitive 
to  certain  colors,  66;  bromide  of  sil- 
ver, 91. 

Bromine,  75 ;  preparation  of,  75. 

Bromo-iodized  collodion,  greater  capacity 
for  colors,  66,  67. 

Bromo-iodizing  solution  for  printing  by  de- 
velopment, 263. 

Bronzing,  334. 

C 

Cadmium,  symbol,  combining  proportions, 
specific  gravity,  71 ;  iodide  of,  67,  73. 

Calcium,  symbol,  combining  properties, 
specific  gravity,  71 ;  iodide  of,  72. 

Calotype,  discovery  of,  17, 18 ;  how  to  sen- 
sitize, 171 ;  Prichard's  process,  180  ; 
Geoffray's  process,  178;  Tillard's  pro- 
cess, 180.    (Vide  Talbotype.) 

Camera,  34,  42 ;  invention  of,  42 ;  must  be 
horizontal  for  architectural  purposes, 
43  ;  stereoscopic,  164 ,  if  tilted,  how  to 
rectify  the  error,  164;  where  to  place, 
165;  camera  stand,  165. 

Camarsac,  Lafon  de,  276. 

Camel's-hair  pencil.  '225. 

Camphene,  in  transfer  paper,  151. 

Canada  balsam,  in  varnish,  150 ;  for  black 
varnish,  138. 


Cap,  used  as  an  instantaneous  shutter,  170. 

Carbon,  reducing  agent,  94 ;  lampblack  in 
black  varnish,  138;  in  Fargier's  pro- 
cess, 280 ;  in  Poitevin's,  281 ;  as  ivory 
black  in  Salmon  and  Garnier's  process, 
279 ;  in  Pouncy's  process,  277 ;  print- 
ing, 20 ;  process,  275 ;  processes  with 
the  salts  of  iron,  281 ;  print,  how  to 
transfer,  283. 

Carbonate  of  lime,  preparation  of,  190 ;  in 
toning  formulas,  (chalk,)  202. 

Carbonate  of  soda,  preparation  of,  190 ;  in 
toning  formulas,  202. 

Card-picture,  218 ;  coloring  of,  224. 

Celestial  photography,  320. 

Cerolein,  178, 179. 

Centigrade  scale,  340,  341. 

Chaldeans,  10. 

Champlouis,  (De,)  improvement  in  the  wax- 
paper  process,  176. 
Chardon,  276. 

Chemical  equivalents,  table  of,  344. 

Chestnut-colored  hair,  227. 

Chimenti's  drawings  not  stereoscopic,  318. 

Chinese  vermilion,  225 ;  Chinese  white,  225. 

Chlorides,  76;  of  lime,  78;  chlorinetted 
lime,  78 ;  of  gold,  187,  203 ;  of  silver, 
photographic  properties  of,  93;  of  sil- 
ver used  for  dry-plating  and  galvano- 
plasty,  93  ;  of  silver,  12, 17. 

Chloroform,  solvent  of  varnish,  137, 139 ;  in 
black  japan,  150. 

Chromotype,  22. 

Citrate  of  iron,  279 ;  of  soda,  106, 190. 

Citric  acid,  105  ;  uses  of,  106. 

Clarifying  operation  of  negatives,  154. 

Claudet's  developer,  169. 

Cleaning  and  polishing  the  silver  plate,  (Da- 
guerreotype,) 268 ;  the  surface  of  the 
photo-lithographic  print. 

Clippings  of  prints,  207. 

Coating  the  glass,  (wet  process,)  129 ;  the 
paper  with  the  sensitive  solution  photo- 
lithography, 304. 

Collodion,  19 ;  decomposition  of,  61,  62 ; 
least  stable,  64 ;  most  permanent,  64 ; 
sensitizers,  65;  for  tannin  plates,  246; 
plain  or  normal,  79 ;  "iodized,  79  ;  bro- 
mo-iodized, 79,  80;  Wortley's,  Lieut. - 
Col.  Stuart,  formula  of,  80;  Omme- 
ganck's  formula  of,  81 ;  Disderi's  for- 
mulas of,  81 ,  82,  83  ;  wet  process,  127 ; 
positives,  127, 136 ;  negatives,  144 ;  pos- 
itives on  glass,  153  ;  dry-process,  232  ; 
collodio-albumen  process,  237,  241 ;  for 
Taupenot  plates,  238 ;  formula  of  Col. 
Sir  H.  James,  303 ;  imperfections  of  nega- 
tives, 326 ;  remedies  of,  326,  etc. 

Coloring,  of  collodion  positives,  136 ;  of  a 
card-picture,  224 ;  of  a  portrait,  225 ; 
of  the  face,  226,  228,  229. 

Colors,  not  rendered  permanent  in  helio- 
chromy, 323. 

Comparison  of  hydrometric  indications, 
342 ;  of  weights  and  measures,  337 ;  of 
thermometric  indications,  340,  341. 

Condensers,  157. 

Contrast  of  light  and  shade,  127 ;  excess 

of,  cause  of,  322 ;  deficiency  of,  321. 
Copal,  soft  varnish,  157;  with  benzole,  137. 
Copies,  for  the  engraver  to  work  from,  296. 
Copying  of  collodion  negatives  or  posi- 


INDEX. 


347 


tives,  160, 161,  162 ;  of  any  given  size, 
253. 
Copernicus,  10. 

Copper,  requires  a  strong  etching  fluid, 
296. 

Corrosive  sublimate,  125. 
Crookes,  320. 
Crysotype,  273. 

Crystalline  lens,  moved  by  ciliary  muscle, 
311. 

Cyanide  of  potassium,  119, 120, 155 ;  a  re- 
ducing agent,  121. 
Cyanogen,  118 ;  preparation  of,  118. 
Cyanotype,  273. 

D 

Davanne,  298. 

David  Hilaire,  231. 

Daguerre,  13, 14,  15, 16. 

Daguerreotype,  268 ;  latent  image  brought 
out  by  mercury,  15,  270. 

Dark-room,  46,  47  ;  what  it  contains,  47,  48. 

Defects,  in  the  printing  of  negatives,  333 ; 
in  the  paper,  333;  defective  sensitiz- 
ing, 333;  defective  toning,  334;  defec- 
tive fixing,  335. 

Deficiency  of  contrast  in  the  negative,  cause 
of,  331. 

Definition,  imperfect,  cause  of,  332. 

Developers,  94 ;  negative,  145,  146 ;  sul- 
phate of  iron,  114, 115 ;  Disderi's,  115 ; 
Lieut.-Col.  Stuart  Wortley's,  116,  168 ; 
Meynier's,  116  ;  Hockins's,  116,  169  ; 
Waldack's,  116,  117;  Claudet's,  169; 
Crookes's,  177 ;  De  Champlouis's,  177 ; 
too  intense,  cause  of  fogging,  328. 

Developing,  solutions,  114,  213;  the  pic- 
ture, (wet  process,)  131,  132;  Fother- 
gill's,  243;  Col.  Sir  H.  James's,  303; 
of  the  silver  plate,  270. 

Development,  of  the  card-picture,  219 ;  of 
the  albumen  film,  237 ;  of  the  Taupe- 
not  plates,  239 ;  of  the  tannin  plates, 
247,  248. 

Diffused  light,  in  the  camera,  cause  of  fog- 
ging, 326 ;  in  the  dark-room,  etc.,  cause 
of  fogging,  328. 

Direct  rays  of  the  sun  through  the  axis  of 
the  lens,  cause  of  fogging,  327. 

Distances,  long  and  short,  seen  at  the  same 
time,  310,  312 ;  theories  about,  311 ;  dif- 
ferences of,  313. 

Distillation  of  the  nitrate-bath,  112. 

Distortion,  from  too  great  contrast  of  light, 
27. 

Dolland,  9. 

Doublet,  35. 

Donne,  287. 

Draper,  Dr.,  use  of  hot  water  in  the  tannin 

process,  248. 
Drying  the  positive  plate,  (wet-process,)  135. 
Drying  process,  of  albumen  films,  235. 


E 

Eclipses,  photographed,  322. 
Edwards,  321. 
Electric  telegraph,  10. 
Electricity,  a  reducing  agent,  95. 
Elements  of  matter,  table  of,  344. 


Enamels,  how  to  make,  309. 

England,  formula  for  collodion  for  the  tan- 
nin process,.  249. 

Engraving,  photographic,  286 ;  heliographic, 
296 ;  on  the  daguerreotype  plate,  286 
290. 

Etching,  fluid,  289,  290 ;  of  the  plate,  295 ; 
on  glass,  296  ;  on  zinc,  306. 

Ether,  55 ;  how  to  prepare,  58  ;  property  of, 
on  collodion,  61. 

Ethyle  group,  55. 

Eureka  plate,  140. 

Excelsior  plate,  140. 

Exposing  the  glass,  (wet  process),  131. 

Exposure  of  the  silver  plate,  (Daguerreo- 
type,) 269  ;  photo-engraving,  293 ;  un- 
der the  negative,  (photo-lithography,) 
304. 

Eye,  its  philosophy,  311 ;  single  eye  cogni- 
zant of  relief,  311. 


F 

Fahrenheit,  scale,  340,  341. 
Fargier,  275. 

Feebleness  of  the  negative  image,  cause  of, 

331. 
Ferrier,  119. 

Ferreotype  plates,  apt  to  blister  in  the  dry- 
ing, 143. 

Field  photography,  rules  to  be  observed,  44. 

Films,  tender  and  rotten,  cause  of,  332. 

Fixation  of  the  Taupenot  plates,  239. 

Fixing,  solutions,  118,  121 ;  the  picture, 
(positive  —  wet- process,)  133 ;  solu- 
tions for  negatives,  147 ;  solutions  for 
prints,  203  ;  of  the  card-picture,  221 ; 
of  the  image,  (Daguerreotype,)  270. 

Fizeau,  16. 

Flowing  the  varnish,  in  photo-engraving, 

292. 

Focus,  of  a  lens,  (how  to  find,)  36,  43,  44; 
equidistant  conjugate,  36,  254,  255 ; 
principal,  254 ;  equivalent,  254 ;  actinic 
and  luminous,  (coincidence  of,)  39. 

Fogginess,  remedy  for,  134,  326,  327,  328. 

Fogging,  111. 

Formic  acic,  a  reducing  agent,  95. 
Forrest,  321. 

Formula  for  zinc  «namel,  307. 

Fothergill  process,  242. 

French  government,  16. 

Fumes  of  ammonia,  cause  of  fogging,  328. 

Fumigation  of  the  asphaltum  film,  294. 

Fuminating,  apparatus,  199 ;  process,  198.  . 


G 

Gallic  acid,  a  reducing  agent,  95 ;  prepara- 
tion of,  100. 
Gallo-nitrate  of  silver,  17. 
Galls,  Aleppo,  306. 
Garnier,  275. 

Gelatine,  185 ;  operation,  (tannin-process,) 
245 ;  process,  244. 

Geoffray,  process  with  cerolein,  178. 

Glass,  actinic,  32 ;  non-actinic,  46 ;  house, 
28,  29 ;  plates,  (preparation  for  Taupe- 
not plates,)  23S ;  vignette,  223;  how 
to  clean,  303. 


348 


INDEX. 


Globe  lens,  165. 

Glover's  reshiized  printing  process,  210. 
Glycyrrhizine,  makes  collodion  sensitive, 
63. 

Gold,  deposited  by  galvanism,  287  ;  chlo- 
ride of,  187,  203  ;  gold  and  uranium 
toning,  202. 

Grain,  engravers,  298. 

Gramme,  5337. 

Granulation,  Aqua-tinta,  (how  made,)  2S9  ; 

application  of,  294. 
Grape-sugar,  makes  collodion  sensitive,  63. 
Gray  hair,  how  to  color,  228. 
Green  drapery,  229. 

Gum,  arable,  187 ;  guaicum,  12 ;  mastic, 
210  ;  thus,  210 ;  sandarac,  varnish  for 
cold  plate,  139. 

Gutta-percha  baths,  cause  of  fogging,  328. 


H 

Hardwick's  views  about  the  decomposition 

of  collodion,  02,  63. 
Harshness,  or  excess  of  contrast,  cause  of, 

332. 

Harrison,  C.  C,  41 ;  Globe  lens,  165. 

Hartnup,  321. 

Heat,  a  reducing  agent,  95. 

Heliochromy,  22 ;  or  the  art  of  taking  pho- 
tographs in  their  natural  colors,  323. 

Heliography,  11,  14;  heliographic  engrav- 
ing, Negre's  process,  296. 

Herschel,  Sir  John,  15,  IS,  323. 

Hipparchus,  10. 

History  of  photography,  9. 

Hockins,  Developer,  116, 169. 

Hodgson,  821. 

Hoffmeister,  131. 

Holmes,  Booth  and  Hayden's,  41. 
Honey,  308. 
Horn  silver,  92. 

How  to  improve  the  color  of  transparent 
positives,  253. 

How  to  take  diminished  copies  of  photo- 
graphs, 265. 

How  to  take  enlarged  copies  of  photographs, 
262. 

now  to  transfer  the  carbon  print  from  glass 

to  paper,  2S3. 
Hydriodic  acid,  70. 
Hydrobromic  acid,  76. 
Hydrocyanic  acid,  119. 
Hydrogen,  a  reducing  agent,  94. 
Hydrometers,  342. 
Hydrosulphocyanic  acid,  120. 
Hyposulphite  of  soda,  120, 121. 


I 

Illumination,  for  copying  different  from 
that  in  portraiture,  162,  163. 

Image,  imperfections,  theory  of,  325. 

Image,  solid,  314,  315. 

Imperfections,  in  collodion  negatives  and 
their  remedies,  326,  etc. ;  fogginess,  326, 
in  paper  prints,  333 ;  in  albumenizing 
and  salting,  833 ;  washing  previous  to 
toning,  334. 

India-rubber  for  black  varnish,  138. 

Inking,  of  the  bichromate  print,  304. 


Instantaneous  process  of  Lieut.-Col.  Stu- 
art Wortley,  167 ;  shutters,  169 ;  stere- 
ographs, 166. 

Intensifies,  122,  147,  168,  242;  Sir  II. 
James's,  302. 

Intensifying,  first  method,  147,  148,  123 ; 
second  and  third  do.,  124. 

Iodides,  65 ;  alkaline  all  soluble,  65 ;  tests 
of  purity,  74 ;  preparation  of,  69 ;  im- 
purities of,  73. 

Iodide,  of  potassium,  not  very  soluble,  65 ; 
of  ammonium,  easily  decomposed,  65 ; 
of  silver,  sensitive  to  certain  colors, 
65 ;  of  cadmium,  glutinizes  collodion, 
67 ;  alkaline,  liquefies  collodion,  67 ; 
of  barium,  71 ;  of  calcium,  72 ;  of  lith- 
ium, 72 ;  of  potassium,  72 ;  of  sodium, 
73 ;  of  ammonium,  73. 

Iodine,  69 ;  of  cadmium,  73 ;  of  silver,  pre- 
paration of,  90;  properties  and  tests 
of,  70. 

Iodizers,  certain  ones,  cause  of  fogging,  327. 

Iodized  albumen,  233,  234,  240,  241. 

Iodizing  for  gelatine,  tannin  process,  246 ; 
of  wax  paper,  174. 

Iron,  developer  for  negatives,  145, 146 ;  sul- 
phide of,  98  ;  protosalts  and  persalts  of. 
97,  98. 

J 

James,  Col.  Sir  Henry,  21,  301,  308. 
Japan,  black,  150. 

Joubert's  prbcess  for  taking  photographs  on 

glass  in  enamel  colors,  308. 
Jupiter  and  his  bands  photographed,  322. 


K 

Keene's  Rapid  dry  process,  250. 
Kaiserstuhl,  11. 


L 

Lace,  how  to  imitate  in  colors,  231. 
Lampblack,  for  black  varnish,  138. 
Landscape,  photography,  164. 
Lavender,  oil  of,  11. 

Legray,  wax-paper  process,  178 ;  first  sug- 
gested the  use  of  gun-cotton,  51. 

Lens,  34 ;  crossed,  34 ;  how  to  buy  a  good  one, 
39 ;  single  equivalent  to  a  compound,  37 ; 
axis  of,  254 ;  optical  centre  of,  254 ; 
principal  focus  of,  254 ;  conjugate  foci 
of,  254  ;  equivalent  focus  of,  254 ;  equi- 
distant conjugate  focus,  224  ;  vertex  of, 
254;  how  to  find  the  principal  focal 
distance  of,  254 ;  how  to  find  where  the 
lens  is  to  be  placed  in  the  solar  micro- 
scope, 260. 

Lenses,  for  the  card-picture,  219  ;  compara- 
tive value,  36  ;  magnifying  power,  37  ; 
Harrison's,  Ross's,  Dallmeyer's,Grubb's, 
Jamin's,  Holmes's,  Booth  and  Hayden's, 
Voightlaender's,  41. 

Lerebours,  298. 

Light,  action  of,  96 ;  a  reducing  agent,  95  ; 

single,  162 ;  velocity  of,  102  ;  must  enter 

from  the  north. 
Lime,  carbonate  of,  190. 


INDEX. 


349 


Linseed  oil,  rubbed  into  an  engraved  plate, 
28T. 

List  of  a  photographic  outfit,  25,  26. 
Lithium,  71 ;  iodide  of,  72. 
Litre,  337. 
Lunar  caustic,  88. 

M 

Macrophotography,  257,  262. 
Manipulation,  of  positive  printing,  192. 
Marbled  appearances  in  the  paper,  333. 
Marion's,  Preserving  box,  210. 
Mars,  photographed,  322. 
Mats,  139. 

Matter  for  the  reception  of  the  image,  23. 

Materials  used  in  positive  printing,  183. 

Mayo's  Outlines  of  Human  Physiology,  312. 

Mealiness,  on  the  print,  336.  . 

Melainotype,  23  ;  plate,  apt  to  blister  in  the 
drying,  143. 

Mercury,  bichloride  of,  125;  vapor  of  a  de- 
veloper, 15,  270  ;  preparation  of,  bichlo- 
ride of,  125 ;  bichloride  of,  an  intensi- 
fier,  169 ;  developer,  275. 

Metals,  how  to  imitate  in  colors,  230. 

Metre,  337. 

Modified  albumen  process,  240. 

Modified  collodio-albumen  process,  (James 

Mudd's,)  241.  mm 
Monckhoven,  (Van,)  272 ;  his  views  about 

the  decomposition  of  collodion,  61,  62. 
Moon,  photographed,  321;  stereographed, 

321. 

3ST 

Negatives,  for  enlargement,  262 ;  for  card- 
pictures,  221 ;  collodion,  144 ;  enlarge- 
ment by  the  camera,  157 ;  on  paper, 
171;  definition  of,  24;  developer  for, 
145,146. 

Negre's  process,  296. 

Newton's,  photo-lithographic  process,  300. 
Nicephore  Niepce,  asphaltotype,  291,  297. 
Niepce,  14,  15, 16. 
Niepce,  Isidore,  16. 

Niepce  de  St.  Victor,  18,  22,  233 ;  on  helio- 

chomy,  323. 
Nitrate  of  silver,  photographic  properties 

of,  88,  89 ;  bath,  109,  110,  111 ;  cause 

of  fogginess,  327. 
Nitric  acid,  a  reducing  agent,  95. 
Nitro-glucose,  preparation  of,  63. 
Non-azotized  substances,  186. 
Norris,  Dr.  Hill,  process,  244. 


O 

Oil,  of  bergamot,  in  varnish,  149  ;  of  laven- 
der, 21. 

Ommeganck's  formula  for  collodion,  SI. 
Osborne,  20. 

Ounce,  avoirdupois,  100 ;  Troy,  100. 
Over-development,  cause  of  fogging,  334. 
Oxide  of  silver,  how  to  prepare,  110. 


P 

Paper,  albumenized,  194 ;  arrowroot,  19! 


for  transfer-process  in  photo-litho- 
graphy, 304. 

Pearl-gray,  color,  230. 

Pension,  16. 

Persalts  of  iron,  97,  98. 

Phosgene  gas,  13. 

Phosphate  of  soda,  190. 

Photographic-ware  baths,  110. 

Photography,  11;  Celestial,  320;  photo- 
graphic engraving,  286. 

Photographs,  mounting  of,  205,  206  ;  photo- 
graphic properties  of  chloride  of  silver, 
93. 

Photo-lithography,  297 ;  asphalto-photo-lith- 
ographic  process,  297  ;  photo-zinco- 
graphy, 297;  first  attempts  at,  297; 
Newton's  process,  300  ;  Osborne's,  301 ; 
Col.  Sir  H.  James's,  301 ;  photo-typo- 
graphic process,  300;  photo-lithograph- 
ic ink,  304 ;  photo-papyrography,  308. 

Physiology,  10. 

Pink  drapery,  229. 

Pictures,  red,  green,  violet,  blue,  274,  275. 

Ponton  Mungo,  19. 

Poitevin,  20,  21,  270,  299,  300. 

Porta,  42  ;  Giovanni  Battista  Delia,  312. 

Positive,  printing  on  paper,  182  ;  transpar- 
ent by  contact,  159. 

Positives,  collodion,  127 ;  alabastrine,  140  ; 

Potassium,  71 ;  cyanide  of,  119  ;  sulpho- 
cyanide  of,  120 ;  sulphide  of,  125  ;  iodide 
of,  72. 

Preliminary  observations,  23. 

Preparation,  of  salted  paper,  192 ;  of  the 
plates  of  steel,  etc.,  for  photo-engrav- 
ing ;  of  the  glass ;  wet  collodion  process, 
128, 129. 

Preservers,  139  ;  preservative,  solution,  Dr. 
Hill  Norris,  244 ;  tannin  plates,  247. 

Printing,  of  sensitized  paper,  200 ;  without 
the  salts  of  silver,  272 ;  with  the  chlo- 
ride of  silver,  191 ;  by  development, 
212 ;  directly  on  paper  by  means  of 
the  sesqui-chloride  of  iron  and  tartaric 
acid,  285 ;  of  card-pictures,  222  ;  direct, 
182 ;  transparent  by  contact,  159 ; 
transparent  by  the  dry-process,  252. 

Process,  Pouncy's  carbon,  277  ;  Salmon  and 
Garnier's  carbon,  27S  ;  Fargier's  carbon, 
275,  2S0 ;  carbon  with  the  salts  of  iron, 
281 ;  for  colored  pictures,  274,  275 ; 
albumen,  233;  dry  collodion,  232; 
Humbert  de  Molard,  180 ;  Prichard's 
Calotype,  180;  Talbotype,  172;  wax- 
paper,  173;  Geoffray's,  178;  Tillard's, 
179;  Niepce  de  St.  Victor,  216;  Fumi- 
nating,  198;  Resin,  249;  Rapid  dry, 
250;  Bertrand's,  209  ;  Glover's,  210; 
drying  of  albumen  films,  235;  Fother- 
gilPs,  242 ;  Taupenot's,  237 ;  Dr.  Hill 
Norris's,  244  ;  Tannin,  245 ;  Tannin  and 
Honey,  248 ;  Fizeau's,  (similar  to  that 
of  Donne,)  2S7  ;  Negre's,  296  ;  asphalto- 
photo-lithographic,  297  ;  bichromo-pho- 
to-lithographic,  299 ;  photo-typographic, 
300;  Newton's,  (photo-lithographic,) 
300  ;  Joubert's  (colored  enamel,  308. 

Prussic  acid,  119. 

Pyrogallic  acid,  a  reducing  agent,  95 ;  pre- 
paration of,  101 ;  developers,  115, 146. 

Pyroxyline,  51 ;  preparation  of,  52,  53  ;  for- 
mulas for  making,  53,  54,  55. 


350 


INDEX. 


Q 

Quality  of  the  paper  used  in  the  transfer 
process. 

R 

Radiant,  axis  of,  254. 

Rapid  dry  process,  250. 

Rays,  direct  and  parallel,  159. 

Reaumur's  scale,  340,  341. 

Red,  hair,  (coloring  of,)  227  ;  tone  owing  to 
defective  toning,  334;  drapery,  (color- 
ing of,)  229. 

Redeveloping  process,  14T. 

Reflections  within  the  camera,  cause  of  fog- 
ging, 326. 

Reflectors,  used  as  condensers,  157. 

Resin  process,  249. 

Retina  of  the  eye,  not  a  surface,  310. 

Rice  water,  174. 

Ridges  and  undulating  lines  in  the  negative, 

330. 
Ritter,  12. 

Rose-colored  drapery,  (coloring  of,)  229. 

Roulette,  9. 

Royal  Society,  15, 16. 

Rue,  (De  la,)  321,  322. 

Russell,  (Major,)  245. 


S 

Salmon,  275 ;  Salmon  and  G-arnier's  carbon 
process,  278. 

Salted  paper,  (formulas  for,)  192. 

Salting  solutions,  (for  printing  by  develop- 
ment,) 212,  213. 

Salts  of  iron,  (printing  with,)  273 ;  in  carbon 
processes,  281 ;  of  uranium,  printing 
with,  273. 

Saturn  and  his  rings,  photographed,  322. 
Scale,  thermometric,  340,  341. 
Scheele,  12. 

Scott,  Captain,  improvements  in  photo-litho- 
graphy, 301. 

Screens,  31 ;  with  graduated  tints,  31 ;  pic- 
torial, 31. 

Seebeck,  12. 

Self-acting  washing  machine,  205. 

Sensitizing,  solution,  (James  Mudd's,)  241 ; 
solution,  (James  Larpey's,)  240;  of 
Taupenot's  plates,  239  ;  of  the  albumen- 
film,  235 ;  substances,  24 ;  (nitrate  of 
silver,)  110,  111 ;  the  collodion  film,  (wet 
process,)  130 ;  (nitrate  of  uranium,) 
216,  217;  defective,  333;  plain  silver 
bath,  196 ;  ammonio-nitrate  bath,  197  ; 
for  development,  214,  215,  216;  the 
daguerreotype  plate,  269  ;  of  wax- 
paper,  175. 

Sesquichloride  of  iron,  285 ;  formula  of,  in 

carbon  process,  281. 
Side-light,  29. 

Silver,  oxide  of.  110;  iodide  of,  90,  110; 
chloride  of,  92,  191  ;  salts,  84 ;  reduc- 
tion of,  85,  86,  87 ;  nitrate  of,  88 ;  pho- 
tographic properties  of  the  nitrate  of, 
8S,  89 ;  hyposulphite  of,  90 ;  sulphate 
of,  90 ;  bromide  of,  91 ;  tests  of  the  chlor- 
ide of,  93  ;  photographic  properties  of 
the  chloride,  93. 


Sir  Humphry  Davy,  13. 
Soda,  citrate  of,  106,  190 ;  hyposulphite  of, 
120  ;  acetate  of,  190  ;  phosphate  of,  190. 
Sodium,  71 ;  chloride  of,  191 ;  iodide  of,  73. 
Solarization,  cause  of,  332. 
Soleil  and  Dubosc,  312. 
Solution  for  transfer  paper,  151. 
Solvent,  of  the  asphaltum  film,  293. 
Specialties,  27. 

Specific  gravity,  comparison  of,  342. 
Spectrum,  12. 

Spots  and  apertures  in  the  negative,  328, 
329  ;  opaque,  329  ;  transparent,  329,330. 
Starch,  186. 
Steam-engine,  10. 

Stereograph,  instantaneous,  116, 167;  stereo- 
graphic  negatives,  164;  strabonic,  314, 
315 ;  how  to  see  strabonic  stereographs, 
316,  317 ;  Towler's,  319. 

Stereoscope,  Wheatstone's,  312 ;  mere  optical 
contrivance,  315. 

Stereoscopicity,  theory  of,  310. 

Stone,  for  photo-engraving,  298,  299. 

Streaks  and  stains,  cause  and  remedy,  331. 

Sugar  of  milk,  Legray's  formula,  174. 

Suitable  rooms,  27. 

Sulphate  (double)  of  ammonia  and  iron,  98 ; 
sulphate  of  silver,  90. 

Sulphide  of  iron,  98  ;  of  potassium,  (prepara- 
tion of,)  125 ;  of  ammonium,  125. 

Sulphocyanide  of  potassium,  120;  of  ammo- 
nium, 120. 

Sulphovinic  acid,  58. 

Sulphurous  acid,  58. 

Sulphuric  acid,  58. 

Sun,  easily  photographed,  321. 

Sutton,  19  ;  rapid  dry  process,  250. 

Symbols  of  elementary  bodies,  344. 


T 

Table  for  increasing  or  diminishing  the  size 
of  a  picture,  256. 

Talbot  Fox,  16, 17,  21. 

Talbotype?  17, 171 ;  process,  172. 

Tannic  acid,  a  reducing  agent,  95 ;  prepara- 
tion of,  99. 

Tannin  process,  245;  and  honey  process, 
248 ;  preservative,  249. 

Tartaric  acid,  preparation  of,  107 ;  printing 
with,  285. 

Taupenot  process,  237. 

Temperature  modifies  development,  103. 

Telescopes,  reflecting  and  refracting,  320. 

Tillard,  turpentine  and  wax  process,  179. 

Toning  of  prints,  201 ;  formulas,  202 ;  of 
card-pictures,  224  ;  first  effect  of,  204 ; 
of  the  silver  plate,  (daguerreotype,)  271. 

Transfer  paper,  20,  151 ;  process,  of  collo- 
dion pictures,  150 ;  ink,  307;  solution, 
151 ;  of  carbon  print  from  glass  to 
paper,  283. 

Transference  of  the  print  to  zinc  or  stone, 

305. 

Transparent  positives,  153,  159,  285,  289; 

by  the  dry  process,  252. 
Triplet,  35. 

Turpentine,  in  transfer  solution,  151. 
Twaddell's  hydrometer,  842,  343. 
Tyrolese  Alps,  11. 


INDEX. 


351 


u 

Under-exposure,  the  cause  of  fogging,  334. 
Unit,  English  linear,  French  linear,  337. 
Undulating  lines  on  the  negative,  330. 
Uranium,  printing  with,  273 ;  and  gold  ton- 
ing, 202  ;  nitrate  of,  189. 


V 

Varnish  of  Niepce  de  St.  Victor,  291 ;  for 
collodion  pictures,  137, 139 ;  black,  138, 
139  ;  applied  cold,  139. 

Varnishing  of  collodion  positives,  136. 

Vergennes,  formula  of,  256. 

Vicar  of  Wakefield,  32. 

Vignette-printing,  223. 

Vinci,  Leonardo  da,  on  binocular  vision,  311. 

Violet  color,  230  ;  colored  glass  for  focussing 
actinically,  39. 

Virtual  solid  image,  314. 

Vision,  binocular,  312. 


W 

Waldack's  developers,  116, 117. 
Washing  machine,  (self-acting,)  205 ;  of  the 
solvent,  (asphaltotype,)  294. 


Watt,  9. 

Wax-paper  process,  173. 

Wedgwood,  13,  14. 

Weight  of  water,  62,  338. 

Weights,  apothecaries  and  avoirdupois,  338 ; 

and  measures,  337,  339 ;  comparison  of. 

838. 

Wet-paper  process,  Molard's,  180. 

Wheatstone's  reflecting  stereoscope,  312. 

Whey,  (serum,)  174,  175. 

White  hair,  (coloring  of,)  228  ;  drapery,  ^co- 
loring of,)  229 :  wax  in  black  varnish. 
138. 

Wollaston,  12. 

Work-room,  what  it  contains,  49,  50. 
Wortley's  (Lieut.-Colonel  Stuart)  collodion 

formulas,  80,  167  ;  developer,  116, 168 ; 

intensifier,  168. 
Wood-spirit,  104. 


Y 

Yellow  drapery,  (coloring  of,)  229. 
Yellow  tone  in  the  whites,  its  cause,  335. 


Z 

Zinc  enamel,  307 ;  white,  30T. 


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erally that  they  are  now  prepared  to  satisfy  the  popular  demand  for  it,  and 
to  furnish  it  in  any  quantity  promptly.  This  Varnish  has  the  highest  repute 
among  the  most  successful  artists  in  the  country,  and  will  continue  to  be 
made  under  the  personal  care  and  direction  of  Mr.  R.  A.  Lewis,  which  is  a 
sufficient  guarantee  for  the  quality  of  it  in  future.  Price,  50  Cts.  per  Bottle. 

Lewis  &  Holt's  Varnish  and  H.  B.  &  H.'s  Eureka  Plates  are  sold  by 
Stock  Dealers  everywhere. 


HOLMES,  BOOTH  &  HAYDENS, 
No.  49  CHAMBERS  STREET,  N.  Y. 


EDWARD  AND  HENRY  T.  ANTHONY, 

No.  501  Broadway,  New- York, 

MANUFACTURERS  AND  IMPORTERS  OP 

PMoppMc,  Autotype  and  Daguerreotype  Materials 

OIT  lE^HE^Y  DESCRIPTION. 


Agents  for 

COLEMAN  SELLER'S  PATENT   PHOTOGRAPHIC  PRESS. 

MOWRY'S  PHOTOGRAPHIC  PRESSES. 

F.  SI.  V.  PLATES  FOR  POSITIVE  PHOTOGRAPHS. 

C.  C.  HARRISON'S  CAMERAS. 

WOODWARD'S  SOLAR  CAMERA. 

ATWOOD'S  PATENT  ALCOHOL. 

SUTTON'S  "PHOTOGRAPHIC  NOTES." 

THE  "BRITISH  JOURNAL  OP  PHOTOGRAPHY." 

DR.  HILL  NORRIS'S  DRY  COLLODION  PLATES. 

PEARSELL'S  PATENT  UNIVERSAL  PLATE-VICE. 

Mannfactiarers  of 
DAGUERREOTYPE  CASES,  embracing  many  new  styles. 
ANTHONY'S  CELEBRATED  COLLODION. 

FLINT  VARNISH  FOR  NEGATIVES. 

DIAMOND  VARNISH. 

BLACK  VARNISH,  THAT  WILL  NOT  CRACK. 
**  •  NEGATIVE  GUN-COTTON. 

ALBUMENIZED  PAPER. 
PATENT  PHOTOGRAPHIC  ALBUM. 
PURE  IODIDES  AND  BROMIDES. 
NITRATE  OF  SILVER. 
CHLORIDE  OF  GOLD. 
AURO-CHLORIDE  OF  SODIUM. 
INSTANTANEOUS  STEREOSCOPIC  VIEWS. 

IMPORTERS  OF 

The  Genuine  Saxe  and  Rive  Paper,  Purple  Glass,  Crown  Glass,  Glass 
for  Negatives,  the  Best  French  Chemicals,  Filtering  Papers,  etc. ; 
Passe-Partouts,  Fancy  Frames,  Bristol  Boards,  etc.;  Stereo- 
scopic Views,  Cartes  de  Visite  of  Celebrities,  Albums,  etc. 

DEALERS  IN 

Apparatus,  Mattings,  Preservers,  Plates,  Gilt  Frames,  Card  Mounts, 
Mounting  Board,  and  every  thing  required  by  the  Dealer,  Operator, 
or  Amateur. 

PHOTOGRAPHIC  BACKGROUNDS, 

Fancy,  Plain,  or  Landscape. 
 •  •  •  

Edward  and  Henry  T.  Anthony, 

No.  501  Broadway, 
MANUFACTURERS  OF  PHOTOGRAPHIC  ALBUMS. 


PAT E  N  T 


PHOTOGRAPHIC  WARE  BATHS 

The  Greatest  Photographic  Discovery  of  the  Age. 

MADE  EXPRESSLY  FOR  THE 

PUKPOSE  OF  HOLDING  SOLUTIONS 

USED  IN  THE  PRACTICE  OP 
AND 


THE  BEST  ARTICLE  EVER  INTRODUCED 

FOR  THAT  PURPOSE. 




They  can  be  had  with  or  without  the  overflow,  as  maybe  preferred.  They 
are  also  made  to  be  used  as  field-baths,  for  out-door  practice,  and  can  be 
fitted  with  a  cover,  so  as  to  be  perfectly  air-tight.  They  are  found  to  possess 
every  qualification  that  can  be  called  for,  besides  innumerable  advantages 
over  any  other  in  use.  They  hold  the  least  quantity  of  solution,  being  made 
very  thin.  They  will  not  burst  and  let  out  the  silver  solution  like  the  gutta- 
percha bath.  They  will  not  turn  the  solution  black,  as  will  the  rubber  bath. 
They  will  not  check  like  the  porcelain,  nor  crack  from  changes  of  tempera- 
ture, like  the  glass  baths.  They  are  entirely  impervious  to  all  acids,  will 
withstand  all  atmospheric  changes,  are  made  by  a  scientific  man  on  strictly 
scientific  principles,  and  will  last  a  lifetime.  Is  anything  more  required  of 
a  bath  ? 


OEETIFIOATES !  OEETIFIOATES ! ! 

There  are  no  arguments  like  these.  Where  persons  have  used  the  Photo- 
graphic Ware  Baths  and  indorse  them  thoroughly,  their  testimony  convinces 
the  most  incredulous.   Kead  the  following : 

From  New- York  City  Operators. 

"  I  would  say — for  the  benefit  of  the  Photographic  and  Ambrotype  profession  generally — 
that  for  over  three  years  past  I  have  used,  and  at  the  present  time  am  using,  in  my  three 
establishments  in  New-York  City,  no  other  kind  of  Bath  than  the  one  described  above,  and 
believe  it  to  be  the  best  and  only  reliable  article  now  in  use.  I  have  tried  all  others,  and 
none,  except  the  Photographic  Ware,  was  without  objection.  I  feel  confident  that  all  who 
may  give  them  a  trial  will  never  have  cause  to  regret  it.  I  have  now  seven  in  daily  use, 
which  any  one  so  disposed  can  see  by  calling  at  my  establishments. 

"  J.  H.  YOUNG,  145  and  198  Eighth  Avenue,  N.  Y." 


"  371  Broadway,  New- York. 
11  Having  used  the  Photographic  Ware  Bath  since  its  first  introduction,  I  have  the  utmost 
confidence  in  its  utility,  and  consider  it  by  far  the  best  article  now  in  use  for  holding  the 
solutions  required  in  the  practice  of  the  photographic  art.  I  find  it  perfectly  safe  and  free 
from  all  liability  to  crack  or  check  like  the  common  porcelain  in  market,  and  it  will  not 
cause  any  stain  or  destroy  the  silvering  solution,  which  so  often  occurs  when  the  gutta- 
percha or  India-rubber  Baths  are  used.  I  can  not  recommend  the  Photographic  Ware  Baths 
too  strongly  to  the  favorable  consideration  of  all  who  wish  a  safe,  reliable,  and  perfect  article. 

"C.  W.  GRAY." 


From  a  Southern  Operator. 

u  I  have  been  using  the  Photographic  Ware  Baths  in  my  establishment  ever  since  their 
introduction,  having  been  the  purchaser  of  the  very  first  one  sold.  Time  has  shown  that 
these  Baths  are  perfectly  unexceptionable.  I  consider  them  to  be  every  thing  that  the 
Photographer  can  desire.  For  no  consideration  would  I  be  without  them,  or  return  to  the 
use  of  gutta-percha  or  porcelain — having  seen  enough  trouble  with  them  before  the  intro- 
duction of  the  Photographic  Ware.        B.  P.  PAGE,  Proprietor  of  Plumb  Gallery, 

Washington,  D.  C." 

"As  Operator  for  Mr.  Page,  I  have  daily  witnessed  the  advantages  and  superiority 
of  the  Photographic  Ware  Baths,  and  cheerfully  indorse  the  above.      JOHN  GOLDIN." 


From  Western  Operators. 

"  ,  Illinois,  June  11. 

•  "  You  ask  how  I  got  along  with  the  Photographic  Ware  Baths.  They 
sell  first-rate.  I  have  some  orders  for  No.  3,  field,  without  the  overflow.  I  sell  six  of  the 
Photographic  Ware  Baths  to  one  of  any  other  kind.      Yours  truly,      P.  JOHNSON." 


"  ,  Ohio,  Oct.  5. 

•  "  Don't  fail  to  send  me  a  lot  more  of  those  Photographic  Ware  Baths 
with  the  next  goods  you  ship.  My  customers  have  got  a  taste  for  them,  and  nothing  else 
will  go  down.  One  Operator  says  he  has  saved  over  fifty  dollars  by  their  use  already ; 
he  is  not  afraid  of  bursting  and  letting  out  the  silver,  as  his  old  gutta-percha  one  did. 
And  then  they  are  so  cheap  !  I  shall  want  one  dozen  each  of  Nos.  1,  2,  and  3,  and  six  of 
No.  4.  JOHN  H.  FISHER." 

11 1  have  just  been  witnessing  the  use  of  the  Photographic  Ware  Baths,  which  I  can  not 
do  without ;  send  one  of  No.  4,  and  I'll  make  you  a  present  of  my  Porcelain  Bath — that 
is,  if  you  will  pay  express  charges  on  it  to  your  city.  L.  B.  BARNES." 


Extract  from  the  London,  Dictionary  of  Photography,  {by  Thomas  Sutton,  Esq., 
the  Editor  of  Photographic  Notes,)  page  131 : 

*  "  Porcelain  Baths  are  very  objectionable,  as  nitrate  of  silver  acts  on 
the  glaze.  There  is  a  substance  used  in  America  for  baths  and  dishes  called  PHOTO- 
GRAPHIC WARE,  which  resembles  Wedgewood  Ware,  and  has  no  glaze ,  this  answers 
the  purpose  admirably." 


Extract  from  Humphrey's  Journal,  27b.  5,  Vol.  XL. 

"  The  Photographic  Ware  Baths  were  first  made  by  George  Mathiot,  Esq.,  of  the^ United 
States  Coast  Survey  Office,  Washington,  for  his  own  use.  A  friend  of  his,  an  artist,  was 
struck  with  their  neatness,  durability,  and  cheapness,  and  also  their  special  adaptation  to 
the  use  to  which  they  were  put.  He  advised  Mr.  M.  to  take  out  a  patent  for  them  at  once, 
which  he  did,  and  now  the  whole  Photographic  fraternity  have  the  benefit  of  them  at  about 
one  half  the  price  of  any  other  kind  of  bath.  Those  who  have  tried  them  once  will  never 
again  return  to  glass,  porcelain,  or  gutta-percha,  each  of  which  is  objectionable,  besides 
costing  twice  as  much." 


LIST  OF 

1-4  $0  75 

1-2   1  00 

4-4   2  00 


PRICES. 

9  by  11  $3  00 

11  by  15   5  00 


They  can  be  had  of  all  Stock-Dealers  in  the  United  States,  and  in  New- 
York  of  the  following  houses : 

HOLMES,  BOOTH  &  HAYDENS  ; 
SCOVILL  MANUFACTURING-  COMPANY; 
EDWARD  &  HENRY  T.  ANTHONY ; 
J.  W.  WILLARD  &  CO. 


New-York,  September  15, 1863. 


SHAW'S  APPARATUS 

FOR 

SAVING  SILVER  AND  GOLD 


FROM  WASTE  SOLUTIONS. 


According  to  many  experiments  made  on  this  side  of  the  Atlantic,  as 
well  as  in  Europe,  to  ascertain  the  amount  of  silver  contained  in  Photo- 
graphs, Negatives,  etc.,  it  is  found  that  a  very  large  proportion  of 
all  the  silver  used  is  actually  thrown  away  and  lost,  three  quarters  being 
the  lowest  estimate  made  of  the  amount  thus  wasted.  Experience  has 
taught  that  a  large  proportion  of  this  useless  waste  of  the 

PRECIOUS  METAL  CAN  BE  SAVED 

by  the  use  of  the  above  Apparatus,  which  has  been  in  successful  operation 
for  the  past  year  with  good  results.  And  I  propose  to  put  it  in  the  hands 
of  every  Photographer  in  the  United  States  upon  such  terms  as  shall  be 
practically  without  cost.  I  therefore  propose  to  furnish  the  Apparatus  to 
every  one  applying  for  it, 

FREE  OF  EXPENSE, 

who  will  set  it  up  and  follow  the  instructions  for  using  it,  (which  are  very 
simple,)  upon  the  following  terms  : 

If  I  refine  only  such  waste  as  the  Apparatus  saves  —  hitherto  a  dead 
loss  —  I  will  return  half  the  amount  without  cost  of  refining,  my  propor- 
tion to  pay  for  rent  of  Apparatus,  use  of  Patent,  etc. 

If,  however,  the  Operator  will  deliver  to  me 

ALL  SCRAP  AND  WASTE 

he  can  save  by  following  my  directions,  I  will  refine  it  without  cost,  and 
return  three  fourths,  retaining  one  fourth  for  services,  etc.,  as  mentioned 
above. 

By  the  last  method  I  can  return  more  money  to  parties  using  my  Patent 
than  they  can  possibly  realize  by  saving  in  any  other  manner,  even  if  they 
could  refine  the  waste  for  nothing,  as  my  invention  will  save  a  much  larger 
per  centage.  My  object,  in  making  this  liberal  offer,  is  to  remove  all  temp- 
tation to  infringe  my  Patent. 

To  carry  out  this  plan,  and  at  the  same  time  to  assure  parties  that  they 
will  be  perfectly  secure  respecting  their  just  share  of  the  amount  so  recov- 
ered, I  have  associated  myself  with  a  responsible  party  well  known  to 
a  large  proportion  of  the  Photographers  throughout  the  United  States.  I 
have,  therefore,  placed  the  entire  management  of  the  business  in  the  hands 
of  Mr  O.  S.  POLLETT,  with  Scovill  Manufacturing  Co., 
No.  4  Beekman  Street,  New-York. 

P.  S. — All  Orders  must  be  sent  to  his  address  as  above  given. 

J.  SHAW. 


PHOTOGRAPHIC  BACKGROUNDS. 


ASHE,  DAYTON  &  CO.. 

159  &  161  MERCER  ST., 


(Between  XIoustorA 
and  Bleecker,  / 


ON  HAND  OR  TO  ORDER. 

IMITATION  OE  SEAL  BALUSTEADES,  PILLAES,  Etc. 

Plain  or  Fancy  Landscapes,  Boudoir,  Battle-Field,  Gothic  or  Park 

Scenery;  also  Photogene  Reflectors. 

N.  B.— Packed  and  sent  with  safety  to  all  parts  of  the  world.   Blue  Posting  for  Skylights. 


REFERENCES: 


New-York.— C.  D.  Fredricks  & 
Co.,  Gurney  &  Son,  Brady,  Mead 
&  Brothers,  Lewis,  Thompson, 
Kimball,  Bills,  Remington,  Kert- 
son,  Loud,  Hallett,  Holmes,  Farris, 
Johnson  Brothers,  Root,  Bogardus. 

Brooklyn. — Williamson,  Bills. 

Baltimore. — J.  H.  Young,  Ben- 
dam  Brothers,  Israel  &  Co.,  Moltz. 

Philadelphia. — Broadbent  &  Co., 
Gutekunst,  Germon,  Shriber. 

Boston. — Silbee,  Case  &  Co.,  J. 
W.  Black. 

New-Haven. — Burwell,  Wells  & 
Collins. 

Hartford.— -S.  H.  Waite,  G.  W. 
Davis,  Prescott  &  Gage,  Wilson, 
Kellogg  Brothers. 

Springfield. — D.  B.  Spooner. 

Albany. — J.  H.  Abbott,  Greene 
&  Parsons,  Woodworth,  Denison, 
Couchman. 


W.  J. 


TJiiea. — S.   S.  Rounds, 
Baker. 

Syracuse. — Sayer,  Howland,  Ta- 
bor Brothers. 

Ithica. — Beardsley  Brothers. 
Rochester. — J.  S.  Crocker. 
Buffalo. — B.  F.  Powelson. 
Chicago. — S.  M.  Fassett. 

Indiana,  Fort  Wayne. — William 
Dunkleburg. 

Cincinnati. — Peter  Smith. 

Toronto,  Canada  West. — E.  J. 
Palmer,  J.  P.  Carson. 

Havana,  Cuba. — Fredricks  &  Co., 
Conner. 

Matanzas,  Cuba.  —  Adams  & 
Cady. 

Izquierdo,  Mexico. — Carlos. 
Valparaiso,  Chili. — Pedro,  San- 
ches. 

London. — Stereoscopic  Company. 
Rue  de   Cologne,   Paris.  —  Do 
La  Yergnc. 


DAGUBRRE  MANUFACTURING  CO, 

93  CROSBY  STREET, 


PHOTOGRAPHIC, 

DAGUERREOTYPE, 

AND  AMBROTYPE 


OF  A  SUPERIOR  QUALITY,  MANUFACTURED  AND  CONSTANTLY  ON 
HAND,  AND  FOR  SALE  AT  REASONABLE  PRICES. 


This  Company  are  now  prepared  to  fill  orders  for  all  kinds  of  Photo- 
graphic Chemicals,  and  they  warrant  all  their  goods  to  be  of  a  superior 
quality.  They  guarantee  to  make  as  good  Chemicals  as  can  be  produced  in 
this  or  any  other  country.    They  pay  particular  attention  to 

Nitrate  of  Silver,   Chloride  of  Oold,  Solvable 
Cotton,     Collodions,  "Varnislies, 
Iodides,  Bromides,  JStc. 

They  will  fill  orders  for  Collodion,  both  Positive  and  Negative;  also 
Positive  and  Negative  Varnish,  and  pack  the  same  in  such  style  and  with 
such  labels  as  may  be  desired.  Stock-Dealers  in  the  country,  who  are  in  the 
habit  of  ordering  goods  to  be  put  up  with  their  own  labels,  are  requested 
to  give  us  a  trial,  and  we  will  guarantee  satisfaction. 

OPERATORS  AND  AMATEURS  ! 

Be  sure  and  give  us  a  trial  before  purchasing  elsewhere.  Try  our  Cotton, 
vfarranted  equal  to  the  French !  Try  our  Gold !  Two  ounces  of  Soluble 
Cotton  will  be  sent  in  an  envelope,  prepaid,  on  receipt  of  One  Dollar  and 
Fifteen  Cents.  Address 

DAGUEKBE  MATtfUPACTUKIIG  CO., 

POST-OFFICE  BOX  3490, 

NEW-YORK  CITY. 


DISHES !  DISHES!  DISHES! 


SOMETHING  NEW  AND  USEFUL  I 

The  Photographic  Ware  Baths  having  had  such  a  continued  popularity 
ever  since  their  first  introduction  to  the  public  some  years  since,  the 
manufacturers,  in  order  to  oblige  numerous  customers,  who  have  long 
been  inquiring  for  DISHES  to  be  made  of  the  same  materials  as  the  Baths, 
have  now  the  pleasure  of  offering  their  new  style  of 

Since  their  first  introduction,  a  year  since,  the  demand  for  these  popular 
Dishes  has  been  indeed  unprecedented.  They  are  driving  out  of  the 
market  all  other  kinds.  In  fact,  many  of  the  dealers  neither  offer  nor 
recommend  any  other  kind,  for  the  very  good  reason  that  none  others  give 
satisfaction.  Their  advantages  are  patent.  They  will  not  crack  or  check 
as  a  porcelain  dish  is  sure  to  do,  nor  will  they  drop  to  pieces,  as  we  have 
seen  the  rubber  dishes  do,  and  they  are  entirely  impervious  to  all  acid 
solutions.  They  are  very  strong,  and  will  last  an  operator  as  long  as  he 
continues  in  business.  Do  not  fail  to  order  the  Photographic  Ware 
Dishes,  if  you  want  to  get  the  full  value  of  your  money.   They  can  be  had 


FIVE  DIFFERENT  SIZES,  NAMELY  : 


5  by  7  $0  50 

7  by  9   0  75 

8byl0   1  00 


10  by  12  $1  50 

12  by  16   2  75 

and  other  sizes  will  goon  be  furnished. 


Thomas  Sutton,  Esq.,  Editor  of  the  London  Photographic  Notes,  says, 
"The  Photographic  Ware  answers  the  purpose  for  Baths  and  Dishes 
admirably,"  and  he  ought  to  know  something  about  them. 

For  Sale  by  all  Stock-Dealers. 

New-York,  September  1,  1 863. 


THE  BEST  COLLODION  IN  USE  IS 

LEWIS    &  HOLT'S 

POSITIVE   AND  NEGATIVE, 

With  a  printed  Formula  accompanying  each  bottle.  Being  among  the  first 
in  this  country  to  make  Collodion  Pictures,  they  can  warrant  it  to  be  one  of 
the  best  in  use  ;  also  their 

ADAMANTINE  VAMISH, 

For  Ambrotypes,  Negatives  and  Melainotypes. 

This  Yarnish,  when  applied  to  Negatives,  dries  in  a  few  seconds  perfectly 
hard,  and  does  not  lower  the  intensity,  or  soften  by  the  heat  of  the  sun,  in 
Printing.  It  gives  a  beautiful  gloss  and  brilliancy  to  Ambrotypes.  For 
sale  by  Stock  Dealers  generally, 

PREPARED  BY 

3FL .     jSL.  LEWIS, 

152  CHATHAM  STREET,  NEW-YORK. 

DODGE  &  LEAHY, 

113  Washington  Street,  {First  Floor,)  Boston, 

WHOLESALE  DEALERS  IN 

|»HOTO0fcAt»M0  $T0C& 

HARRISON'S,  VOIGHTLANDER  &  SON'S,  and  JAMIN 

TUBES  AND  LENSES. 

FRAMES  OP  EVERY  DESCRIPTION, 

Black  Walnut,  Rosewood,  French  Polish,  and  Gilt,  manufactured  by  our- 
selves. French  Ovals,  with  and  without  Passe-partout.  The  best  and 
cheapest 


In  America ;  the  best  Steel  Presses  for  Cards  and  Photographs ;  Apparatus 
of  all  kinds  ;  Chemicals,  Glass,  Cases,  Photographic  Ware  Baths  and  Dishes, 
and  every  article  which  the  Photographer  may  need. 

The  Trade  is  respectfully  invited  to  call  or  send  their  orders. 
All  Goods  warranted  to  give  perfect  satisfaction. 


JOHN  STOCK  &  CO., 

No.  2  RIVINGTOISr  STREET, 

NEAR  THE  BOWERY, 

DKT  E  "W-"3T  ORK, 

Beg  leave  to  call  the  attention  of  Amateurs  and  the  profession  generally  to  their  new 
patented  and  improved  Camera  Boxes,  which  consist  of  the  following  :  the 

IMPERIAL  CAMERA, 

Fpr  taking  Pictures  both  in  the  Gallery  and  in  the  Field. 


For  all  kinds  of  work — single  pictures,  four  on  one  plate,  and  for  copying. 

THE  IMPERIAL  FOLDING  CAMERA, 

For  copying ;  adapted  for  field  and  gallery  use. 

STEREOSCOPIC  CAMERAS, 

Double  and  single,  with  the  Patent  Dry  Plate  Box  ;  together  with  their  adjustable 

O^HVEEZR-A.  TABLE. 

This  Table  is  the  most  useful  and  convenient  article  ever  offered  to  the  public,  and  is  much 
admired  by  all  first-class  Artists.  J.  S.  &  Co.  would  especially  introduce  to  your  notice 
their  Patent  Glass  Bath,  universally  adopted,  and  celebrated  in  every  particular  as 
the  tested,  perfect,  and  only  reliable  Glass  Bath  in  the  market.  They  would  also  call  your 
particular  attention  to  their  new  Patent 

DRY-PLATE  BOX  AND  CAMERA, 

This  Box  and  Camera  has  been  thoroughly  tested,  and  is  admitted  by  those  who  are  compe 
tent  to  judge,  to  be  the  best  arrangement  for  field  work  ever  introduced.    They  have  also 
just  patented  an  entirely  new  instrument, 

THE  EXCELSIOR  CAMERA, 

Differing  from  any  thing  heretofore  known.  The  Camera  is  folding, 
with  Baths  attached,  for  taking  pictures  in  the  field  or  drawing-room 
in  direct  sunlight,  without  the  use  of  a  tent  or  dark  room.  This 
instrument  will  not  occupy  more  than  six  square  inches  when 
folded,  including  all  the  apparatus  but  the  tripod.  It  is  indispensa- 
ble for  taking  instantaneous  views  or  portraits  of  deceased  persons. 
J.  S.  &  Co.  would  also  inform  their  friends  and  patrons  that  they 
continue  to  manufacture 

Every  style  of  Instrument  used  in 
.  :  Photography, 

BKss*"  At  the  shortest  notice,  and  every  article  is  warranted. 


PURE  PHOTOGRAPHIC  CHEMICALS. 


SEELY  &  BOLTWOOD, 

E  MIST-, 

No.    24:4=    CANAL  STREET, 

MANUFACTURE  THE 

VARIOUS  CHEMICALS 

USED  BY  PHOTOGEAPHEES, 

Of  the  best  materials,  and  according  to  the  most  approved  processes.  Their 
Chemicals  have  the  highest  repute  among  the  most  successful  Artists,  and 
are  commonly  recognized  as  the  Standard,  for  the  most  desirable  qualities 
of  Uniformity,  Reliability,  and  Purity. 


THEIR  CELEBRATED 


PHOTOGRAPHIC  COLLODION 

Is  unsurpassed  for  the  Harmony,  Delicacy,  and  Strength  of  the  nega- 
tives which  it  invariably  gives  under  the  usual  treatment.  The  great 
excellency  of  the  Collodion  is  mainly  due  to  the  Gun  Cotton  and  the 
Pure  Iodides  and  Bromides  which  enter  into  its  composition,  as  well  as 
to  the  recipe  after  which  it  is  manufactured.  In  addition  to  their  stock  of 
Chemicals,  the  subscribers  are  constantly  supplied  with  the  very  best 


3) 


PLAIN  AND  ALBUMENIZED. 

Orders  should  be  addressed, 

SEELY  &  BOLTWOOD, 

CHEMISTS, 

244  CANAL  BTSEET,  HEW-YOEK. 


E.    M.  OOEBETT, 

MANUFACTURER  OF 

PHOTOGRAPHIC, 

AMBROTYPE,  AND  DAGUERREOTYPE 


Camera  Boxes,  Plate  Holders,  Camera  Stands,  and 
Printing  Frames  made  in  the  Best  and 
Cheapest  Manner. 

NEW  IMPROVED  CAMERA  STAND  ! 


THE  GREATEST  INVENTION  OF  THE  DAY. 

PATENT   APPLIED  FOR. 

Has  an  ingenious  arrangement  for  elevating  the  Camera  to  any  required 
height.  Is  in  use  in  all  the  leading  Galleries  in  this  city  and  elsewhere. 
No  operator  can  afford  to  be  without  one  of  these  Stands. 

ALSO  MANUFACTURER  OF 

COLUMNS,  PEDESTALS,  AND  EAILS, 

SUITABLE  FOR  CARTES   DE  VISITE. 

CAMERA  BOXES, 

With  two  or  four  Tubes  for  Stereoscopic  and  Card  Pictures  ;  all  with  the 
latest  improvements ;  cheap  for  Cash. 

REPAIRING  DONE  AT  THE  SHORTEST  NOTICE. 


Room  22,  New-Haven  IPreiglit  Depot, 

FRANKLIN  STREET,  BETWEEN  CENTRE  AND  ELM, 


AU  orders  thankfully  received  and  promptly  attended  to. 


JAMES  WILCOX, 

No.   10  SPRING  STREET,  NEW-YORK, 

MANUFACTURER  AND  DEALER  IN 

PHOTOGRAPHIC  AND  AMBROTYPE 


MATERIAL 


OF  EVERY  DESCRIPTION, 

[nyites  the  attention  of  Photographers  to  his  extraordinary  advantages  for 
he  supply  of  all  kinds  of  Photographic  Material,  embracing  the  different 
styles  and  makes  of  all  the  principal  manufacturers  of 

GAMEEAS,  APPAEATUS, 

OASES,  MATS  AID  PEESEEVEES 

COLLODIONS,  VAEUISHES, 
AND  CHEMICALS  IK  GENEEAL. 

Also  to  his  new  Eagle  Plates,  which  are  pronounced  by  all  Artists  to 
be  superior  to  any  other  Plates  in  the  market,  and  are  sold  at  the  following 
low  rates : 

1-9  size,  box  of  eight  dozen,  -  -  $0  75 
1-6  "  "  "  "  -  -  -  1  00 
1-4    "       "        "       "  2  00 

1-2  "  "  four  u  -  -  2  25 
4-4    "    per  dozen,    -       -       -  1  16 


I  would  particularly  solicit  a  trial  of  my  ALB  UMENIZED  PAPER, 
"  Saxe"  or  "Rives"  Heavy,  Medium,  or  Light,  which  I  am  making  after  a 
method  differing,  in  several  important  respects,  from  that  of  any  other  manu- 
facture. A  single  trial  is  sufficient  to  convince  any  Artist  of  its  many 
superior  qualities.  Among  them  may  be  mentioned:  freedom  from  spots, 
streaks,  etc.  ;  purity  and  brilliance  of  tones  ;  vigor  of  picture  produced  ;  ease 
of  manipulation  by  all  processes  at  present  in  use;  saving  of  gold  and 
silver.  All  these  have  been  repeatedly  proved  by  its  constant  use,  to  the  ex- 
clusion of  all  other  manufactures,  at  the  establishments  of  the  following  well- 
known  Artists, 

J.  Gurney  &  Son,  Broadway.  A.  Bogardus,  Broadway. 

R.  A.  Lewis,  Chatham  Street.  Geo.  W.  Holt,  Broadway. 

E.  M.  Douglass,  Brooklyn.  R.  Anson,  Broadway. 

Each  of  these  Artists  (the  principal  ones  in  New- York  and  vicinity)  uses 
from  one  to  five  reams  weekly. 

JAMES  "WILCOX, 

10  Spring  Street*  Jtfew-York. 


aEO.    .A..  CHAPMAN 

7§   nUdMVE  STREET,  JTEW-FOIUZ, 

MANUFACTURER,  IMPORTER,  AND  DEALER  IN  EVERY  DESCRIPTION  OF 

DAGUERREOTYPE,  AMBIIOTYPE, 


CHAPMAN'S  SAKE  ALBUMEN  PAPER. 

Appreciating  the  necessity  which  exists  for  operators  to  have  a  fine  article 
of  paper,  I  am  paying  particular  attention  to  this  branch  of  the  business, 
and  can  assure  both  dealers  and  operators  that  I  am  producing,  and  am  pre- 
pared to  supply  them  with,  an  article  unequaled  in  the  market. 


CHAPMAN'S  CAMERAS. 

I  will  warrant  all  my  Cameras  to  give  the  most  perfect  satisfaction,  and 
will  refund  the  money  where  they  do  not  do  so. 


Price-List  of  Cameras. 

Plain. 

1-4  size  Tube  and  Lens,  $15  00 


1-3 
1-2 

Extra  1-2 
4-4 

Extra  4-4 
8-4 


20  00 
25  00 
28  00 
45  00 
80  00 


With  central  stops. 
$18  00 
23  00 
30  00 
33  00 
50  00 
85  00 
130  00 


The  1-4,  1-3,  and  1-2  size  Cameras  can  be  furnished  in  matched  pairs  of 
exactly  the  same  length  focus  for  Cartes  de  Visite  and  Stereoscopic  pictures, 
without  extra  charge. 


CHAPMAN'S  O.  XL  IRON  PLATES. 

I  warrant  these  Plates  to.  be  superior  to  most,  and  equal  to  any  plates 
ever  yet  introduced.  I  submit  the  followiug  prices,  which  are  from  fifteen 
to  thirty  per  cent  lower  than  other  makes. 

1-9  size,  per  8  dozen  boxes,  $0  75  I  1-4  size,  per  8  dozen  boxes,  $2  00 
1-6       "       "  "        1  25     I     1-2       u     4      "  2  15 

4-4  size,  per  two  dozen  boxes,  $4. 

At  the  above  prices  it  is  considerably  cheaper  to  use  plates  than  glass. 

A  liberal  discount  to  Dealers  both  on  Cameras  and  Plates, 

GEO-  A.  CHAPMAN. 


BENJAMIN  FRENCH  &  CO., 

IMPORTERS  AND  DEALERS  IN 

PHOTOGRAPHIC 

AND 

AMJ3RQTYPE  MATERIAL 

Embracing  every  article  required  by  the  Artist  or  Amateur. 

$olk  mmn  ron  thh  ohiebhated 

VOIGTLANDEB  &  SON'S  CAMERAS. 

These  Instruments  are  superior  to  any  now  in  use ;  they  work  in  less  time  and  space 
than  any  others  made,  and  can  be  had  in  sets  of  two  or  four  of  exactly  the  same  length 
of  focus.  Also  Agents  for  the  Jamin  Cameras.  Saxe  Positive  and  Albumenized 
Paper,  also  other  kinds ;  all  of  superior  quality.  Photographic  Albums,  Card-board' 
Card-Mounts,  Photographic  Rollers,  Camera  Boxes,  of  every  desirable  style  and  finish. 
French  and  American  Chemicals,  Passe-Partouts,  Paper  Mats,  Cases,  Frames,  Mats  and 
Preservers,  Wholesale  and  Retail  at  the  lowest  Cash  prices. 

BENJAMIN  FRENCH  &  CO., 

No.  159  WASHINGTON  STREET, 

iBOSTonxr. 


HARRISON  CAMERA  FACTORY, 

Office,  458  BROADWAY,  N.  Y. 

The  undersigned  is  now  manufacturing,  in  addition  to  the  C.  C.  Harrison  Camera 
Tubes,  the 

C.  C.  HARRISON  &  S.  SCHNITZER 

©is©®®  ^siisi 

(Patented  in  the  United  States,  England,  and  the  Continent.) 

These  Globe  Lenses  are  especially  adapted  to  the  wants  of  those  making  either 
Views  or  Copies,  as  they  have  an  angle  of  vision  twice  as  comprehensive  as  the  old  View 
or  Orthoscopic  Lens,  and  will,  therefore,  with  a  very  short  focus,  cover  a  large-sized 
plate.  Their  depth  of  focus  is  so  great  that  objects  near  by  and  distant  are  equally  sharp, 
no  matter  on  which  the  focus  is  drawn.  For  copying  they  are  far  superior  to  the  Ortho- 
scopic, as  they  will  give  copies  of  Drawings,  Maps,  etc.,  mathematically  correct.  They 
can  be  obtained  of  various  sizes  from 

2£  inches  Focal  Length  for  Stereoscopic  Plates  to 
17      "         "         "  24x  24  " 

Our  C.  C.  Harrison  Cameras,  manufactured  under  Mr.  C.  C.  Harrison's  direction, 
are  now  made  in  every  respect  perfect,  and  are  guaranteed  superior  to  those  of  the  most 
celebrated  foreign  manufacturers. 

For  the  Carte  de  Visite,  we  have  just  introduced  a  one-third  size  Camera  expressly 
adapted  to  that  style  of  pictures. 

The  C.  C.  Harrison  Cameras  and  the  C.  C.  Harrison  and  I.  Schnitzer 
Patented  Globe  Lenses,  can  be  purchased  from  all  Stock  Dealers.   Orders  should 

°HELS0H  WEIGHT,  458  Broadway,  New-York. 


NEW  PRINTING  FRAME. 


The  undersigned  would  hereby  call  the  attention  of 

PHOTOGRAPHIC  OPERATORS  AND  AMATEURS 

To  the  Newly-invented  and  Patented  Printing  Frame  of  Mr.  J.  E.  Whitney, 
of  St.  Paul,  Minnesota,  an  Operator  of  twenty  years'  experience  and  prac- 
tice. There  have  been  two  or  three  styles  of  printing  frames  in  the  market, 
but  none  which  gave  perfect  satisfaction.  It  took  much  time  to  open  them  ; 

first,  you  open  one  side,  and  then  the  other,  occupying 
a  minute  at  least ;  but  this  frame  can  be  opened  in 
one  second.  It  will  be  noticed,  by  the  accompany- 
ing cut,  that  the  cross-bars  are  separated  in  the  cen- 
tre by  a  semi-circular  spring.  By  taking  hold  with 
the  thumb  and  forefinger  of  each  hand,  and  slightly 
pressing  these  springs,  the  cover  is  instantly  re- 
moved. The  edge  of  the  lid  is  beveled,  causing  the  ends  of  the  bolts  to 
operate  as  springs,  which  gives  an  even  and  constant  graduated  pressure, 
adjusting  itself  to  the  thickness  as  well  as  to  all  unevenness  in  glass.  There 
is  no  possibility  of  breaking  negatives  in  this  frame  as  in  the  old  kinds.  All 
who  have  seen  this  Frame  have  bestowed  upon  it  the  highest  encomiums. 
It  is  universally  pronounced  to  be 

THE  BEST  PHIHTIHS  FB&ME 

ever  introduced,  and  must  have  an  extensive  sale.  Arrangements  are  now 
being  completed  to  manufacture  them  on  a  large  scale.    Parties  wishing 

THE  WHITNEY  PRINTING  FRAME 

will  please  send  their  orders  to  the  undersigned,  who  have  been  appointed 

SOLE  AGENTS  IN  THE  UNITED  STATES 

for  the  Inventor  and  Patentee.  All  persons  are  hereby  cautioned  against 
infringing  on  this  patent  in  any  manner,  as  the  Agents  are  determined  to 
protect  the  rights  of  the  Inventor. 

B5T  All  orders  will  be  filled  in  rotation.  JSS 

ADDRESS 

SCOYILL  MANUFACTURING  COMPANY, 

36  FAKE  BOW  and  4  BEEKMAN  STBEET, 


NEW-YORK. 


HENRY  J.  LEWIS, 

152    CHATHAM  STREET, 

HEW-VOBK, 

Manufacturer  of,  and  Wholesale  and  Retail  Dealer  in  all  kinds  of 

PHOTOGRAPHIC, 

A1IBR0TYPEAND  DAGUERREOTYPE 

APPARATUS, 

Made  in  the  best  and  most  workmanlike  manner, 

Among  which  may  be  enumerated  : 

Portrait  Cameras,  Printing  Frames, 

View  Cameras,  Stereoscopic  Boxes, 

Carte  de  Yisite  Cameras,  Columns, 

Camera  Stands,  Pedestals, 

Patent  Elevating  Camera  Stands,  Glass-cleaning  Yices, 

Lewis's  Patent  Camera  Stands,  '  Photographic  Roller  Presses  for  Cartes 

Lewis's  Patent  Glass  Baths,  de  Yisite. 

Lewis's  Patent  Yice,  Photographic  Roller  Presses  for  8  x  10 

Lewis's  Patent  Solid  Glass-corner  pictures ;  also  larger  sizes  made  to 

Holders,  order. 
Plate  Holders, 

And  every  thing  in  the  line  of  Apparatus  used  in  the  business  ;  also 

WHOLESALE  AND  RETAIL  DEALER  IN  ALL  KINDS  OP 

CHEMICALS,  STOCK,  AND  MATERIALS 

USED  FOE  PHOTOGRAPHS  OR  AMBSOTYPES. 

Chemicals,  Lewis  and  Holt's  Yarnish, 

Tubes  and  Lenses,  Iron  Plates, 

Oval  Frames,  Card  Mounts, 

Cases,  Glass,  all  sizes. 

Mats,  Albumen  and.  other  Paper  used  for 
Preservers,  Photographic  purposes. 

Lewis  and  Holt's  Collodion. 

P.  S.— Operators  and  Amateurs  in  city  or  country  are  invited  to 
call  before  purchasing  elsewhere.  Goods  sent  to  all  parts  of  the 
world.  TERMS:  CASH. 


E.  GORDON, 

MANUFACTURER  OF 

PHOTOGRAPHIC  APPARATUS, 

AND  DEALER  IN  ALL  KINDS  OF 

STOCK  AND  MATERIALS, 

172  CENTRE    STREET,  NEW-YORK 


CUT  No.  2.  CUT  No.  3. 


Cut  No.  1  represents  his  new  Patent  Card  Camera  Box,  for  two  or  four 
lenses  ;  holder  does  not  move  ;  sets  on  a  carriage  which  moves  so  that  there 
is  no  friction.    Ground-glass  is  hung  on  hinges. 

Cut  No.  2  represents  his  new  Vignette  Printing  Frame,  made  of  tinned 
iron,  having  an  oval  cut  out  of  the  bottom;  the  most  ingenious  thing  of  the 
kind  ever  invented. 

Cut  No.  3  is  a  view  of  his  Patent  Printing  Frame,  of  cast-iron ;  neat  and 
strong.  The  demand  for  this  new  frame  exceeds  the  supply  ;  it  is  destined  to 
supersede  all  others 


PHILADELPHIA. 


A.  P.  BEECHER'S 

PHOTOGRAPHIC  STOCK  DEPOT, 

109  South  Fourth  Street. 

ESTABLISHED  1846. 

DEALER  IN 

VOIGHTLANDER, 

FRENCH  AND  AMERICAN  CAMERAS, 

OASES  AND  FRAMES, 

CHEMICALS,  PHOTOGRAPHIC  PAPER, 

EUREKA  AND  FERROTYPE  PLATES, 

And  all  other  materials  used  in  the  Photographic  Art.    Constantly  on  hand 

Every  Article  used  by  Photographers, 

Of  superior  quality,  and  at  reasonable  prices. 

SAXE  POSITIVE  AND  ALBUMEN  PAPER, 

Of  the  best  quality. 

PHOTOGEAPHIC  PEESSES. 

Porcelain  and  Photographic  "Ware  Baths  and 
Dishes. 

CASES  OF  EVERY  DESCRIPTION. 


GOODS  SENT  EVERYWHERE. 


JOHN  H.  SIMMONS, 

MANUFACTURER,    IMPORTER,    AND  DEALER 

In  every  description  of 

PHOTOGRAPH  AND  AMBROTYPE 


S UPEKIOE  SAXE  ALBUMEN  PAPER. 

Having  devoted  considerable  attention  to  the  manufacture  of  Albumenized 
Paper,  I  have  succeeded  in  producing  an  article  which  it  is  confidently 
believed  will  accomplish  the  desire  so  often  expressed  by  Photographers, 
for  a  paper  economical  in  use,  and  of  absolute  uniformity  in  quality.  The 
manipulation  once  understood,  no  difficulty  will  be  had  in  obtaining  pictures 
of  the  best  quality. 

Always  in  store,  a  full  and  complete  assortment  of  German,  French, 
and  American 

CAMERAS, 

J^JPlPJkJEl AJTTJS,   GLASS,   CASES,  IPIjATTGS, 
CHEMICALS,  Etc.,  Etc. 

A  large  and  full  assortment  of  Gilt,  Rosewood,  Metal,  and  Walnut 
Frames,  constantly  on  hand. 

PHOTOGEAPHIC  ALBUMS 

IN  ENDLESS  VARIETY. 

FINE  BACKGROUNDS, 

Dead  in  color,  and  of  different  shades,  on  hand,  or  made  to  order.  Samples 
furnished  upon  application. 

Depot  for  the  sale  of  Simmons's  unequalled  Positive  and  Carte 

de  Visite 

NEGATIVE  COLLODION, 

And  Preparation  for  the  application  of  Water-Colors  on  Albumen 
Prints,  far  excelling  the  Albumen  Colors  at  present  in  the  market. 

ORDERS  FILLED  ACCURATELY  AND  PROMPTLY. 

ADDRESS 

JOHN  H.  SIMMONS, 

607  CHESTNUT  STREET,  over  Howard's  Express  Office, 


GEORGE  DABBS  &  CO., 

(AT  THEIR  NEW  STORE,) 
333    CHESTNUT    STEEET,    BELOW    FOURTH  STREET, 

PHILADELPHIA,  PENK, 

Manufacturers,  Importers,  and  Dealers  in  every  description  of  Materials  used  for  the 

PHOTOGRAPH,  AMBROTYPE, 

OR 

CAETE  DE  VISITE  PICTURES. 

Agents  for  the  sale  of  the  following  very  celebrated 

Holmes,  Booth  &  Hay-dens'  Patent  Improved ; 
C.  C.  Harrison's  Celebrated  Tubes ;  Voightlander 
&  Sons,  and  Jamin's  French. 

These  Lenses  are  all  of  the  highest  order,  are  made  with  and  without  the 
Central  Stops,  carefully  matched  and  adjusted  expressly  for  the  CARTE  DE 
VISITE  Pictures,  with  the  latest  and  most  approved  styles  of  CAMERA 
BOXES. 


Cameras  of  our  own  make  at  reduced  prices,  warranted 
to  give  entire  satisfaction,  or  the  money  refunded. 

The  attention  of  Operators  and  Amateurs  is  particularly  solicited  to  our 
Extensive  Stock,  having  adapted  our  business  to  meet  all  the  demands  of 
the  most  recent  and  popular  developments  of  Photography. 

Particular  attention  is  called  to  our  twelve-inch  PHOTOGRAPHIC 
PRESSES,  which  are  the  best  and  cheapest  in  use.  Large  sizes  of  the  same 
styles  made  to  order.  We  call  especial  attention  to  the  HOWARD  SOLAR 
CAMERA  with  nine-inch  Condensing  Lens,  which  are  far  superior  to  all 
others  now  in  use,  for  quickness  in  printing,  simplicity  of  adjustment,  as  well 
for  cheapness,  we  being  the  principal  Agents  for  the  same. 

Our  Albumenized  Paper,  to  which  we  have  for  months  past  given  particular 
attention,  has  now  reached  a  point  of  excellence  equal  or  superior  to  all  Paper, 
either  Foreign  or  Domestic,  now  in  market.  We  respectfully  solicit  orders 
for  the  same,  as  also  for  the  following,  which  we  have  constantly  on  hand  : 

Frames  and  Cases  of  all  styles  and  sizes,  Mats,  Preservers,  Glass,  Melaino- 
type  Plates  of  the  best  brands,  Chemicals  of  the  very  best  make,  Card 
Boards,  Card  Mounts,  Albumen  Colors,  Photographic  Ware  baths  and 
Dishes,  and  every  kind  of  apparatus  used  in  the  art,  at  reasonable  rates. 

PRICE-LIST   SEJSTT  BY  MAIL. 

Orders  by  Mail  or  Express  punctually  attended  to. 


WESTERN 

f  MtynyMt  awl  &mJmtyp$ti&  §tpt 

 ♦  

PETER  SMITH, 

No.  36  WEST  FIFTH  STREET, 

CINCINNATI,  OHIO, 

IMPORTER,  MANUFACTURER,  AND  DEALER  IN  EVERY  DESCRIPTION  OP 

Ambrotype  and  Photographic 

HAS    FOR   SALE,  AT    THE    LOWEST    CASH  PRICES, 

OAMEEAS,  APPAEATUS, 

MATTINGS,  PRESERVERS,  PLATES ; 

FANCY  FRAMES  AND  CASES; 
PHOTOGRAPHIC  PAPEE  AND  CHEMICALS, 

AND  MATERIALS  OF  EVERT  DESCRIPTION  FOR  PAPER  PICTURES 
AND  AMBROTYPES. 

NITRATE  OF  SILVER, 

CHLORIDE  OF  GOLD,  ALBUMEN  PAPER,  IODIDES  AND  BRO- 
MIDES, VARNISHES,  COLLODION,  ETC. 

E2HT  Goods  all  Fresh,  and  Warranted  to  give  Satisfaction.  «JS3 


ME  LAI  1ST  O  TYPE. 


'EXCELSIOR. 


lit!  PLATES  FOR  POSITIVE  PHOTOGRAPHY. 


These  Plates  still  hold  their  unrivaled  excellency.  They  are  the  first 
Metallic  Plates  ever  made  for  Photographic  purposes,  having  been  intro- 
duced in  1856,  and  although  many  makers  are  imitating  them,  they  stand 
the  acknowledged  best  and  only  reliable  plates. . 

EVERY  PLATE   IS  WARRANTED! 

They  are  put  up  in  compact  paper  boxes,  secured  from  dust  and  rubbing, 
and  every  box  is  encircled  with  a  black  label,  printed  in  gold  letters.  On 
one  end  is  "  Excelsior,"  with  the  number  and  size  of  the  contents  of 
box.  On  the  opposite  end  is  "  Melainotype,"  with  the  number  and 
size  of  the  contents  of  box. 

On  the  front  is — 

m 


MELAINOTYPE. 
N  EPF'S    IRON  PLATES, 
Warranted. 


On  the  reverse  is — 


-3 


PETER  NEFF,  Jr., 

Gambler,  O. 
JAS.  O.  SMITH  &  SONS, 

No.  81  Fulton  St.,  Hew- York. 


The  Retail  Prices  of  1-9,  1-6,  1-4,  1-2,  4-4,  are 
lower  than  the  prices  of  any  other  Plates,  and  a 
very  large  discount  is  allowed  to  dealers. 


PETER  NEFF,  Jr., 

G-AMBIER,  O. 


"W.  H.  TIL  FOR  D, 

DEALER  AND  IMPORTER  OF 

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AND 

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The  Card  Photograph,  an  Appendix  to  the  Third 

Edition  of  a  Treatise  on  Photography.  By  Charles  Waldack.  Price,  Fifty 
Cents. 

Hardwich's  Photographic  Chemistry.  Manual  of  Photo- 
graphic Chemistry,  including  the  practice  of  the  Collodion  Process.  By 
T.  F.  Hardwich,  Lecturer  on  Photography  in  King's  College,  London. 
300  large  12mo  pages,  with  numerous  illustrations.  Price,  One  Dollar  and 
Twenty-five  Cents. 

WalSaek's  Treatise  on  Photography,  containing  complete 
Directions  for  making  Solar  Camera  and  Stereoscopic  Pictures,  Views,  etc., 
including  also  the  New  Toning  Processes,  the  Dry  Collodion  Processes,  and 
all  the  most  recent  Improvements.  By  Charles  Waldack.  Third  Edition. 
Price,  One  Dollar  and  Twenty-five  Cents. 

Theoretical  and  Practical  Photography  on  Glass 

and  Paper,  with  positive  Rules  for  obtaining  intense  Negatives  with  certainty, 
By  F.  B.  Gage.    Price,  Fifty  Cents. 

The  Photograph  Manual :  A  Practical  Treatise,  containing  the 
Cartes  de  Yisite  Process,  and  the  method  of  taking  Stereoscopic  Pictures, 
and  the  Tannin  Process.  Eighth  Edition.  260  pages.  Price,  One  Dollar 
and  Twenty-five  Cents. 

Practical  Manual  of  the  Collodion  Process,  giving  in 
detail  a  method  for  producing  Positive  and  Negative  Pictures  on  Glass  and 
Paper,  Photographs,  Ambrotypes,  Printing  Process,  etc.  By  S.  D.  Hum- 
phrey.   Price,  Twenty-five  Cents. 

Thornthwaite's  Guide  to  Photography,  containing  simple 
and  concise  Directions  for  obtaining  Views,  Portraits,  etc.,  by  the  chemical 
agency  of  Light.  By  W.  II.  Thomthwaite.  88  12mo  pages.  Price,  Thirty 
Cents,  prepaid. 

Humphrey's  Daguerreotype  Process,  giving  the  most 
approved  and  convenient  methods  for  preparing  the  Chemicals,  and  the 
combinations  used  in  the  Art.  By  S.  D.  Humphrey.  Fifth  Edition.  216 
12mo  pages,  bound  in  red  cloth.    Price,  Fifty  Cents  per  copy. 

Humphrey's  Photographic  Operator,  giving  the  whole 
process  of  making  Photographs,  Ambrotypes,  etc.  Single  copies,  Fifty 
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Photography:  A  Treatise  on  the  Chemical  Changes  produced  by 
Solar  Radiation,  and  the  production  of  Pictures  from  Nature,  by  the 
Daguerreotype,  Calotype,  etc.  By  Robert  Hunt.  200  large  12mo  pages, 
bound  in  red  cloth.    Price,  Fifty  Cents  per  copy. 


HUMPHR  EY'S 

Journal  of  Photography. 

EDITED  BY  JOHN  TOWLER,  M.D. 

Published  Semi-monthly,  and  containing  annually  384  pages  of  Original 
and  Selected  Matter,  prepared  with  the  greatest  care.  This  Journal  is 
devoted  to  the  interests  of  the  Operator,  and  has  for  years  past  been  widely 
Known  as  the  best  and  most  valuable  publication  treating  on  the  Helio- 
graphic  Arts.  It  was  established  November  1,  1850,  and  is  consequently  the 
oldest  Photographic  Journal  in  the  world.  It  has  always  been  considered 
a  most  reliable  medium  for  obtaining  information  on  every  thing  relating  to 
the  art  of  Sun-drawing,  and  no  pains  or  expense  will  be  spared  to  enable  it, 
for  the  future,  to  maintain  its  high  and  commanding  position. 

The  present  Editor  holds  an  eminent  position  as  a  scientific  writer  and 
a  practical  photographer,  and  he  is  one  who  can  reach  and  interest  Operators 
in  a  way  that  few  writers  in  this  country  are  able  to  do.  He  will  aim  to 
extricate  Photographers  from  their  numerous  troubles  and  perplexities,  and 
especially  so  through  the  medium  of  u Answers  to  Correspondents,"  which 
department  of  our  Journal  will  be  found  full,  complete,  and  satisfactory. 

NOTICES  OF  THE  PRESS. 


"We  insert  here  a  few  of  the  many  commendatory  notices  of  Sun 
Journal  given  by  the  Press  of  the  United  States  and  England : 

the  heliographic  arts  and  sciences,  to  take 
a  copy  of  the  work." — Sentinel. 

"It  is  indicative  of  talent  worthy  of  the 
"mportant  art  it  is  designed  to  elevate." — 


44  We  have  received  a  copy  of  a  valuable 
Journal  (Humphrey's)  published  in  New- 
York,  which  has  reached  the  18th  No.  of 

Vol.  XI  We  now  have  the 

pleasure  of  quoting  from  our  transatlantic 
coadjutor." — Liverpool  Photo.  Journal. 

"  Humphrey's  Journal  is  practical  as 
well  as  scientific  in  charater." — American 
Journal  of  Science  and  Arts. 

"It  treats  the  subject  knowingly  and 
with  force." — New-  York  Tribune. 

"It  is  both  a  popular  and  interesting 
publication."— Mechanics'1  Magazine. 

"It  is  highly  useful  to  all  who  practice 
'  shadow-catching.' " — Ohio  State  Jour. 

"  The  work  is  neatly  gotten  up,  and  con- 
tains many  interesting  varieties  in  this  new 
field  of  science.'1 — Times. 

"It  should  be  hailed  and  encouraged, 
not  only  by  photographers  themselves,  but 
by  every  lover  of  science  and  art." — The 
Democrat. 

"  We  can  not  too  strongly  urge  all  artists, 
and  those  persons  who  feel  an  interest  in 

TERMS:  TWO  DOLLARS  PER  ANNUM, 

If  paid  in  advance.  Single  Copies  12  Cents. 

Complete  copies  of  Volumes  4,  5,  6,  7,  8,  9,  10,  11,  and  12  for  One  Dollar 
each.    Volumes  13  and  14,  Two  Dollars  each. 

ADVERTISEMENTS  will  be  inserted  at  the  rate  of  One 
Hundred  and  Fifty  Dollars  per  page  per  year. 


American. 

"  This  art  is  entitled  to  its  own  organ, 
which  could  not  have  fallen  into  better 
hands  than  those  of  the  Editor  of  Hum- 
phretps  Journal.'1'' — Transcript. 

"It  is  a  scientific  work  of  interest  and 
usefulness." — Star  of  the  North. 
"  It  is  rich  with  interest."— North  Am. 
"It  contains  all  the  1  improvements.' " — 
Delta. 

"It  teaches  us  how  to  take  our  own 
portraits." — Bee. 

"It  will  cultivate  a  taste  for  photo- 
graphs."— Commercial  Advertiser. 

"  It  should  be  in  the  hands  of  all."— 
Reveille. 

"  It  is  the  photographer's  friend."— Lon- 
don News. 
"  It  should  be  found  in  every  library." — 

Evening  Journal. 


Published  by 


JOSEPH  H.  LADD, 

No.  60  WHITE  STREET,  N.  Y. 


GETTY  RESEARCH  INSTITUTE 


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